Nagamori Mizuka♀

Mizuka is Kouhei's classmate and childhood friend. She is constantly sighing, being made to go along with Kouhei's meaningless jokes. She takes unusually good care of him such as going to his house every morning to wake him up. For clubs, she helps around the orchestra club and plays the cello. She likes milk so much that she can even drink it while eating rice. Mizuka is a cat-lover and has several of them at her house. She tends to add "da yo" and "mon" at the end of her sentences. She worries about Kouhei, wondering if he could suddenly get a girlfriend.

[From Wikipedia]