Threesome ??

Uchi wa Futago de Teippai!

I think these ones are just smut:
1. https://www.mangago.me/read-manga/adult_bl_shorts_dagong_ikson/
2. https://www.mangago.me/read-manga/perfect_connection/
3. https://www.mangago.me/read-manga/friend_secret/
4. https://www.mangago.me/read-manga/beta_count_so_has_changed/

I don't remember if this is threesome until the end tho:
1. https://www.mangago.me/read-manga/deep/