this is confusingly written. do you mean (1) an age gap of 15-20 years or (2) an age gap story about a 15 year old and a 20 year old? **EDIT: SO, now that I know that the answer was 1, here are some recs! --> Koh-Boku & Suki ni Nacchau yo. --> Boku no Omawarisan & Mujaki na Wanko to Nekokaburi (pretty much everything by Niyama is age-gap) --> Page......
https://www.mangago.me/read-manga/koko_wa_yes_to_ittekure/ i think the age gap is around twenty? the seme is mid forties and uke is late twenties

Yuzuru, a yankee with a mean face, requests Satomi, his senpai, to "make him his little brother" in ...

  • Author: kiriyu kiyoi
  • Genres: School Life / Yaoi

Translation complete, more uploads coming soon....

  • Author: Tsuyuhisa fumi
  • Genres: Yaoi / Comedy

Tachibana Sousuke is a handsome honours student who runs into a spot of bad luck one day: he loses h...

  • Author: momoki sae
  • Genres: Comedy / School Life / Yaoi

- this is honestly so cute def one of my faves!! + two faced uke side couple
(After chater 24 it's just repeats of the other chapters!)