Shishunki na Adam - or 'The Adolescence of Adam' if you prefer - is a (gay) porn Light Novel with little to no plot, terrible characters and a really generic art. Mutsuki Fujita is one of the worst protagonists to ever (dis)grace this medium. And the heroines were nothing but archetypes (Kuu, Tsun and Deredere).
It may be tagged as ecchi but everything is so explict that it should obviously deserve a 'Hentai' tag instead. If you're searching for a great read go look somewhere else. But if, instead, you're searchig for 'fap material' then Jackpot!
Here are the list of fetishes/tropes you may find
in this canc... I mean novel:
Along many others. Happy fap... I guess (?).
Story - 1/10
Art - 3/10
Character - 2/10
Enjoyment - 1/10
Overall - 1/10
Similar recommendations for those looking for ecchi stories with actual PLOT:
Darling in the FranXX, GTO (Great Teacher Onizuka), High School DxD, KILL LA KILL, No Game No Life, Sora no Otoshimono, Seireitsukai no Blade Dance, Shokugeki no Souma and Trinity Seven: 7-nin no Mashotsukai.