The manga I looking for is a yaoi where a guy (i would say his age is older teenager but can't remember if he is still in school) one day decided to try anal masturbation and fell in love with it. Now he always anally masturbates and has dildos he likes to use. While his (I'm pretty sure younger) brother's friend was over he was using a dildo and the friend caught him. Then the they get into a relationship. The friend also is in an archery club at his school.

no idea of this manga, but sounds interesting. Can't wait to find out 😀

http://trihoinach.org/co-thuoc-tri-hoi-nach-vinh-vien-khong

It's Ore no Ushiro ni Tatsu na!!, chapters 5 and 6.

Yes!!!! Thank you so much!!!