If you liked the Oyasumi Punpun manga, the Anime-Planet community thinks you'd like:
Both are bleak but occasionally uplifting stories about aging, loss, regret, dreams, romance, those kinds of things. Kurosawa and Punpun are pretty cynical works with some humour thrown in. It would seem that they have similar morales too.
Shuichi Nitori is an elementary school boy with a secret: he wishes he were a girl and likes wearing their clothes. With the right outfit and his cute, effeminate looks, he is often able to convince people that he is someone else - or even something else. Unfortunately, although his best friend and object of affection, Takatsuki, accepts him as he is, she does not return Shuichi’s feelings. Moreover, school is an unforgiving place and Shuichi walks a fine line between liberating his true self and being labeled a freak by all his peers...
Both manga are about children growing into teenagers while dealing with issues like love, the onset of puberty, friendship and feeling disenfranchised or not being accepted for who you are. They're also very similar in that they feature a lot of characters, plotlines and angst. All this is told with an understated social-realist tone: there's not much in the way of melodrama or easy answers in either work.
I wholeheartedly encourage fans of either of these works to check out the other.