[DeepL Translation - needs review] Volume 1 Introduction: Mai Nanase is a high school girl who has trouble keeping up with her classmates' views on love. One day, Mai overhears a conversation between her brother and his friend, Mr. Nishino, in the next room. It was... "Your sister... she's so cute," she heard this line from behind a thin wall...! I'm not interested in romance, but when I hear it, I can't help but be aware of it! This is the first volume of a series of stories about these two...
Note: there is a full color edition, and a b/w edition. If you want the color one, check that the volumes have ［カラー版］ in the title.
Fun romantic comedy that doesn't take itself too seriously, but also isn't exaggerated and unbelievable. The drama is pretty minor and nicely resolved. Main couple are sweet, awkward, and well matched, and so far the side characters (particularly the brother) are just there for convenience. Update: the side characters feature much more prominently as the series progresses, and one of the later ones, Aki, became my favorite character :)
There's some interesting slang and expressions here and there. Certainly the first time I've seen 所帯くさい! Good manga for casual speech. Also, it's full color and full furigana :D
In case you care about things wrapping up cleanly: vol 10 is the final volume, and it really didn't wrap anything up. It's too bad, the development was starting to improve at that point. Overall, decent shoujo though.