Suki ni Nacchau yo.
A university student develops a conversation AI named "DD" and is introduced to a retired sensei who helps him develop it.
Toshishita Kareshi ni Hirowaremashita
When the love of his life marries, Shouta gets drunk and ends up outside a restaurant that shares his love's last name. He's taken home by the owner's high school aged son, Maru, who takes a liking to him.
Yami ni Tooboe, Mune ni Toge
This mangaka is always so creative! A human with a soul bond to a powerful demon is reincarnated into a 17yo high school student who cannot get close to other people, or they end up gravely injured. Also features the bonded demon's hilarious older snake brother and others!
Koi wo Suru Tsumori wa Nakatta
Yoshino celebrates his 30th birthday by visiting a gay bar for the first time, and gives his first time to Rou, an attractive younger guy who is flirty but not serious about him. They put each other through the lack-of-communication roller coaster and end up together, with the promise of (I presume) a ring in the box Rou brought home.
Rakka Ryuusui no Hoshi
An orphaned 19yo sleeps around to bury his loneliness and falls for a cop assigned to stop him. Based on the comments, I expected to like this, but it felt a bit coercive on the part of the cop (especially the last scene) and the relationship exhausted me.
Home (TSUYUKI Yuruko)
A lonely writer is saved by a persistent child who comes to visit him. This veered awfully close to uncomfortable. The writer is open about falling in love with Subaru when he's still a child, though I think it grew from the loss of companionship after Subaru had gone to America and strengthened as he matured. I wish the author had felt saved by a child rather than saying he'd fallen in love with him, and even held that child up on some sort of moral pillar. That might have made for more interesting tension when Subaru returned and erased the skeeve factor.
The Wolf in the Flower Shop
A high schooler raising his younger brother is shocked when he's confessed to by a stranger in a park. This would've been just as effective with a MC who was a fellow shopkeeper rather than a HS student.
Boku no Osekkai Darling
Concerned his adult son is gay, Nobu -- a 47 year old widowed single father -- follows him to the club district where he's mistakenly picked up by Hijiri, who assumes he is a shy client and goes home with him. After a night of drunken sex (dubious in consent since it starts while Nobu is asleep, but in context, Hijiri believed Nobu had hired him to do it), Nobu comes to his senses but turns protector when he learns Hijiri has nowhere to go. Hijiri has a tragic ongoing backstory. His stepfather has assaulted him for years and forced him into the sex industry, which Hijiri agreed to out of guilt since his stepfather took care of him after his mother's death. Nobu steps into a father-of-sorts role with him, dragging him out of the sex club and offering to take over his debts. However, they're always lovers. This wasn't father/son play. They actually come to be pretty fond of each other and by the end get rings. I really wish the stepfather had been thrown in jail, though.
Shishi ni Hire
An older teacher and the former student he inspired, who is now a host, passes for a thug, and loves the hell out of him.
Secrecy