diff --git a/pixivpy3/aapi.py b/pixivpy3/aapi.py
index f6ffd24..639e9e7 100644
--- a/pixivpy3/aapi.py
+++ b/pixivpy3/aapi.py
@@ -69,24 +69,30 @@ def set_api_proxy(self, proxy_hosts: str = "http://app-api.pixivlite.com") -> No
         """Set proxy hosts: eg pixivlite.com"""
         self.hosts = proxy_hosts
 
+    def _url(self, endpoint: str) -> str:
+        return f"{self.hosts}{endpoint}"
+
     # Check auth and set BearerToken to headers
     def no_auth_requests_call(
         self,
-        method: str,
+        method: Literal["GET", "POST"],
         url: str,
         headers: ParamDict = None,
         params: ParamDict = None,
         data: ParamDict = None,
         req_auth: bool = True,
     ) -> Response:
+        # `mypy` doesn't allow type overwriting, must add `_` suffix
         headers_ = CaseInsensitiveDict(headers or {})
+
         if self.hosts != "https://app-api.pixiv.net":
-            headers_["host"] = "app-api.pixiv.net"
-        if "user-agent" not in headers_:
+            headers_["Host"] = "app-api.pixiv.net"
+
+        if "User-Agent" not in headers_:
             # Set User-Agent if not provided
-            headers_["app-os"] = "ios"
-            headers_["app-os-version"] = "14.6"
-            headers_["user-agent"] = "PixivIOSApp/7.13.3 (iOS 14.6; iPhone13,2)"
+            headers_["App-OS"] = "ios"
+            headers_["App-OS-Version"] = "14.6"
+            headers_["User-Agent"] = "PixivIOSApp/7.13.3 (iOS 14.6; iPhone13,2)"
 
         if not req_auth:
             return self.requests_call(method, url, headers_, params, data)
@@ -160,7 +166,7 @@ def user_detail(
         filter: _FILTER = "for_ios",
         req_auth: bool = True,
     ) -> models.UserInfoDetailed:
-        url = f"{self.hosts}/v1/user/detail"
+        url = self._url("/v1/user/detail")
         params = {
             "user_id": user_id,
             "filter": filter,
@@ -178,7 +184,7 @@ def user_illusts(
         offset: int | str | None = None,
         req_auth: bool = True,
     ) -> models.UserIllustrations:
-        url = f"{self.hosts}/v1/user/illusts"
+        url = self._url("/v1/user/illusts")
         params = {
             "user_id": user_id,
             "filter": filter,
@@ -201,7 +207,7 @@ def user_bookmarks_illust(
         tag: str | None = None,
         req_auth: bool = True,
     ) -> models.UserBookmarksIllustrations:
-        url = f"{self.hosts}/v1/user/bookmarks/illust"
+        url = self._url("/v1/user/bookmarks/illust")
         params = {
             "user_id": user_id,
             "restrict": restrict,
@@ -224,7 +230,7 @@ def user_bookmarks_novel(
         tag: str | None = None,
         req_auth: bool = True,
     ) -> models.UserBookmarksNovel:
-        url = f"{self.hosts}/v1/user/bookmarks/novel"
+        url = self._url("/v1/user/bookmarks/novel")
         params = {
             "user_id": user_id,
             "restrict": restrict,
@@ -244,7 +250,7 @@ def user_related(
         offset: int | str | None = None,
         req_auth: bool = True,
     ) -> ParsedJson:
-        url = f"{self.hosts}/v1/user/related"
+        url = self._url("/v1/user/related")
         params = {
             "filter": filter,
             # Pixiv warns to put seed_user_id at the end -> put offset here
@@ -260,7 +266,7 @@ def user_recommended(
         offset: int | str | None = None,
         req_auth: bool = True,
     ) -> ParsedJson:
-        url = f"{self.hosts}/v1/user/recommended"
+        url = self._url("/v1/user/recommended")
         params = {
             "filter": filter,
         }
@@ -278,7 +284,7 @@ def illust_follow(
         offset: int | str | None = None,
         req_auth: bool = True,
     ) -> ParsedJson:
-        url = f"{self.hosts}/v2/illust/follow"
+        url = self._url("/v2/illust/follow")
         params: dict[str, str | int] = {
             "restrict": restrict,
         }
@@ -289,7 +295,7 @@ def illust_follow(
 
     # 作品详情 (类似PAPI.works(),iOS中未使用)
     def illust_detail(self, illust_id: int | str, req_auth: bool = True) -> ParsedJson:
-        url = f"{self.hosts}/v1/illust/detail"
+        url = self._url("/v1/illust/detail")
         params = {
             "illust_id": illust_id,
         }
@@ -304,7 +310,7 @@ def illust_comments(
         include_total_comments: str | bool | None = None,
         req_auth: bool = True,
     ) -> ParsedJson:
-        url = f"{self.hosts}/v1/illust/comments"
+        url = self._url("/v1/illust/comments")
         params = {
             "illust_id": illust_id,
         }
@@ -325,7 +331,7 @@ def illust_related(
         viewed: str | list[str] | None = None,
         req_auth: bool = True,
     ) -> ParsedJson:
-        url = f"{self.hosts}/v2/illust/related"
+        url = self._url("/v2/illust/related")
         params: dict[str, Any] = {
             "illust_id": illust_id,
             "filter": filter,
@@ -359,9 +365,9 @@ def illust_recommended(
         req_auth: bool = True,
     ) -> ParsedJson:
         if req_auth:
-            url = f"{self.hosts}/v1/illust/recommended"
+            url = self._url("/v1/illust/recommended")
         else:
-            url = f"{self.hosts}/v1/illust/recommended-nologin"
+            url = self._url("/v1/illust/recommended-nologin")
         params: dict[str, Any] = {
             "content_type": content_type,
             "include_ranking_label": self.format_bool(include_ranking_label),
@@ -405,7 +411,7 @@ def novel_comments(
         include_total_comments: str | bool | None = None,
         req_auth: bool = True,
     ) -> models.NovelComments:
-        url = f"{self.hosts}/v1/novel/comments"
+        url = self._url("/v1/novel/comments")
         params = {
             "novel_id": novel_id,
         }
@@ -428,7 +434,7 @@ def novel_recommended(
         include_privacy_policy: str | list[int | str] | None = None,
         req_auth: bool = True,
     ) -> ParsedJson:
-        url = f"{self.hosts}/v1/novel/recommended"
+        url = self._url("/v1/novel/recommended")
         params: dict[str, Any] = {
             "include_ranking_label": self.format_bool(include_ranking_label),
             "filter": filter,
@@ -465,7 +471,7 @@ def illust_ranking(
         offset: int | str | None = None,
         req_auth: bool = True,
     ) -> ParsedJson:
-        url = f"{self.hosts}/v1/illust/ranking"
+        url = self._url("/v1/illust/ranking")
         params: dict[str, Any] = {
             "mode": mode,
             "filter": filter,
@@ -481,7 +487,7 @@ def illust_ranking(
     def trending_tags_illust(
         self, filter: _FILTER = "for_ios", req_auth: bool = True
     ) -> ParsedJson:
-        url = f"{self.hosts}/v1/trending-tags/illust"
+        url = self._url("/v1/trending-tags/illust")
         params = {
             "filter": filter,
         }
@@ -510,7 +516,7 @@ def search_illust(
         offset: int | str | None = None,
         req_auth: bool = True,
     ) -> models.SearchIllustrations:
-        url = f"{self.hosts}/v1/search/illust"
+        url = self._url("/v1/search/illust")
         params: dict[str, Any] = {
             "word": word,
             "search_target": search_target,
@@ -553,7 +559,7 @@ def search_novel(
         offset: int | str | None = None,
         req_auth: bool = True,
     ) -> models.SearchNovel:
-        url = f"{self.hosts}/v1/search/novel"
+        url = self._url("/v1/search/novel")
         params: dict[str, Any] = {
             "word": word,
             "search_target": search_target,
@@ -582,7 +588,7 @@ def search_user(
         offset: int | str | None = None,
         req_auth: bool = True,
     ) -> ParsedJson:
-        url = f"{self.hosts}/v1/search/user"
+        url = self._url("/v1/search/user")
         params: dict[str, Any] = {
             "word": word,
             "sort": sort,
@@ -599,7 +605,7 @@ def search_user(
     def illust_bookmark_detail(
         self, illust_id: int | str, req_auth: bool = True
     ) -> ParsedJson:
-        url = f"{self.hosts}/v2/illust/bookmark/detail"
+        url = self._url("/v2/illust/bookmark/detail")
         params = {
             "illust_id": illust_id,
         }
@@ -614,7 +620,7 @@ def illust_bookmark_add(
         tags: str | list[str] | None = None,
         req_auth: bool = True,
     ) -> ParsedJson:
-        url = f"{self.hosts}/v2/illust/bookmark/add"
+        url = self._url("/v2/illust/bookmark/add")
         data = {
             "illust_id": illust_id,
             "restrict": restrict,
@@ -631,7 +637,7 @@ def illust_bookmark_add(
     def illust_bookmark_delete(
         self, illust_id: int | str, req_auth: bool = True
     ) -> ParsedJson:
-        url = f"{self.hosts}/v1/illust/bookmark/delete"
+        url = self._url("/v1/illust/bookmark/delete")
         data = {
             "illust_id": illust_id,
         }
@@ -645,7 +651,7 @@ def user_follow_add(
         restrict: _RESTRICT = "public",
         req_auth: bool = True,
     ) -> ParsedJson:
-        url = f"{self.hosts}/v1/user/follow/add"
+        url = self._url("/v1/user/follow/add")
         data = {"user_id": user_id, "restrict": restrict}
         r = self.no_auth_requests_call("POST", url, data=data, req_auth=req_auth)
         return self.parse_result(r)
@@ -654,7 +660,7 @@ def user_follow_add(
     def user_follow_delete(
         self, user_id: int | str, req_auth: bool = True
     ) -> ParsedJson:
-        url = f"{self.hosts}/v1/user/follow/delete"
+        url = self._url("/v1/user/follow/delete")
         data = {"user_id": user_id}
         r = self.no_auth_requests_call("POST", url, data=data, req_auth=req_auth)
         return self.parse_result(r)
@@ -663,7 +669,7 @@ def user_follow_delete(
     def user_edit_ai_show_settings(
         self, setting: _BOOL, req_auth: bool = True
     ) -> ParsedJson:
-        url = f"{self.hosts}/v1/user/ai-show-settings/edit"
+        url = self._url("/v1/user/ai-show-settings/edit")
         data = {"show_ai": setting}
         r = self.no_auth_requests_call("POST", url, data=data, req_auth=req_auth)
         return self.parse_result(r)
@@ -676,7 +682,7 @@ def user_bookmark_tags_illust(
         offset: int | str | None = None,
         req_auth: bool = True,
     ) -> ParsedJson:
-        url = f"{self.hosts}/v1/user/bookmark-tags/illust"
+        url = self._url("/v1/user/bookmark-tags/illust")
         params: dict[str, Any] = {
             "user_id": user_id,
             "restrict": restrict,
@@ -694,7 +700,7 @@ def user_following(
         offset: int | str | None = None,
         req_auth: bool = True,
     ) -> models.UserFollowing:
-        url = f"{self.hosts}/v1/user/following"
+        url = self._url("/v1/user/following")
         params = {
             "user_id": user_id,
             "restrict": restrict,
@@ -713,7 +719,7 @@ def user_follower(
         offset: int | str | None = None,
         req_auth: bool = True,
     ) -> ParsedJson:
-        url = f"{self.hosts}/v1/user/follower"
+        url = self._url("/v1/user/follower")
         params = {
             "user_id": user_id,
             "filter": filter,
@@ -731,7 +737,7 @@ def user_mypixiv(
         offset: int | str | None = None,
         req_auth: bool = True,
     ) -> ParsedJson:
-        url = f"{self.hosts}/v1/user/mypixiv"
+        url = self._url("/v1/user/mypixiv")
         params = {
             "user_id": user_id,
         }
@@ -749,7 +755,7 @@ def user_list(
         offset: int | str | None = None,
         req_auth: bool = True,
     ) -> ParsedJson:
-        url = f"{self.hosts}/v2/user/list"
+        url = self._url("/v2/user/list")
         params = {
             "user_id": user_id,
             "filter": filter,
@@ -764,7 +770,7 @@ def user_list(
     def ugoira_metadata(
         self, illust_id: int | str, req_auth: bool = True
     ) -> ParsedJson:
-        url = f"{self.hosts}/v1/ugoira/metadata"
+        url = self._url("/v1/ugoira/metadata")
         params = {
             "illust_id": illust_id,
         }
@@ -780,7 +786,7 @@ def user_novels(
         offset: int | str | None = None,
         req_auth: bool = True,
     ) -> models.UserNovels:
-        url = f"{self.hosts}/v1/user/novels"
+        url = self._url("/v1/user/novels")
         params = {
             "user_id": user_id,
             "filter": filter,
@@ -798,7 +804,7 @@ def novel_series(
         last_order: str | None = None,
         req_auth: bool = True,
     ) -> ParsedJson:
-        url = f"{self.hosts}/v2/novel/series"
+        url = self._url("/v2/novel/series")
         params = {
             "series_id": series_id,
             "filter": filter,
@@ -814,7 +820,7 @@ def novel_detail(
         novel_id: int | str,
         req_auth: bool = True,
     ) -> models.NovelInfo:
-        url = f"{self.hosts}/v2/novel/detail"
+        url = self._url("/v2/novel/detail")
         params = {
             "novel_id": novel_id,
         }
@@ -829,7 +835,7 @@ def novel_new(
         max_novel_id: int | str | None = None,
         req_auth: bool = True,
     ) -> ParsedJson:
-        url = f"{self.hosts}/v1/novel/new"
+        url = self._url("/v1/novel/new")
         params: dict[str, Any] = {
             "filter": filter,
         }
@@ -846,7 +852,7 @@ def novel_follow(
         offset: int | None = None,
         req_auth: bool = True,
     ) -> ParsedJson:
-        url = f"{self.hosts}/v1/novel/follow"
+        url = self._url("/v1/novel/follow")
         params: dict[str, Any] = {"restrict": restrict, "offset": offset}
         r = self.no_auth_requests_call("GET", url, params=params, req_auth=req_auth)
         return self.parse_result(r)
@@ -860,7 +866,7 @@ def webview_novel(
         req_auth: bool = True,
     ) -> models.WebviewNovel | str:
         # change new endpoint due to #337
-        url = f"{self.hosts}/webview/v2/novel"
+        url = self._url("/webview/v2/novel")
         params = {
             "id": novel_id,
             "viewer_version": "20221031_ai",
@@ -899,7 +905,7 @@ def illust_new(
         max_illust_id: int | str | None = None,
         req_auth: bool = True,
     ) -> ParsedJson:
-        url = f"{self.hosts}/v1/illust/new"
+        url = self._url("/v1/illust/new")
         params: dict[str, Any] = {
             "content_type": content_type,
             "filter": filter,