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Thirty years old

http://www.mangago.zone/tag/Young%20seme/
Here, this is where you can search tags like that to find manga in any categoryヾ(❀╹◡╹)ﾉ~

Lover Boy is classic!
One of my favorite endings!

i think i have some Σ( ￣□￣||)
*runs to my "already read" list* ε=ε=(ノ ￣□￣)ノ
ok i'm back.
http://www.mangago.zone/read-manga/erotic_m/ I'm pretty sure the uke is older; based off of the subtext, i sort of guessed that he was.
http://www.mangago.zone/read-manga/osananajimi_ga_do_m_de_tsundere_nan_desu_ga/ another one. the uke is 5 years older.
http://www.mangago.zone/read-manga/make_me_bark/?av=2 the 2nd pairing has an older uke too.
http://www.mangago.zone/read-manga/motto_musunde_aite_waya/ seme is a younger co-worker
http://www.mangago.zone/read-manga/grandson_loves_his_grandfather_too_much/ i am so sorry but this one has a seme that is 47 years younger than the uke and yes i know that it's incest but it fit what you were looking for so um-
yeah

ironically, all of these (except for the first one) have a seme that's had a huge crush on the uke for years.