I have noticed that there are two characters named Amano_Hina, one is a main character from Shinkai Makoto's last film, Amano_Hina_(Tenki_no_Ko) who has more than 150 posts and the disambiguation, while the other is Amano_Hina, whoose only post is from an "eroge" visual novel named Lucky Bird from more than a decade ago (source: https://www.animecharactersdatabase.com/sp/characters.php?id=16841 ). Even through it came before, this one doesn't have any relevance compared to the Tenki no Ko character, so is it valid for Amano_Hina_(Tenki_no_Ko) become the main tag (through alias request), while Amano_Hina gets the disambiguation?

I've renamed the tag to amano_hina_(lucky_bird). In cases where multiple characters have the same name, all of them should have the series name as a qualifier. Making one of them the "main" only causes confusion.

In general, if a very large tag conflicts with a very small tag, then it's fine for the large tag to not have a qualifier. In this case they're both relatively small, so it's better to qualify both.