If you're looking for manga similar to Seinen Shoyo yo, Haru wo Musabore, you might like these titles.
A serious hardworking company employee, Arai Kyuta, is an extreme misanthrope who can't take off his mask at his human-ish company. One day, he meets a young girl who looks like a discarded doll…. and their twisted co-ed life begins with a deal…
There's been a string of disappearances in the city where Hyde runs a watchmakers'. Following the disappearance of one of his friends, he encounters a mysterious man who seems to be intent on hunting him down...
The story begins with an image of a girl standing atop a bridge guardrail, but flashes back a few days before that, when a girl on a train accuses a salaryman named Shunta Momochi of molesting her. Another girl named Tesura Nishina raises her hand and comes to his defense, solving the incident before the girl and Shunta get off the train. Together, the "unreasoning" Tesura Nishina and Shunta Momoichi, who just wants to be friends with a high school girl, will explore what Tesura calls "meaningless theories," her term for the mysteries of everyday life.