Itoshi Koishi - Vol. 2 Ch. 12

[MangaDex]

 

[IRLthicc]

Wait……. If she was 17 at the beginning of the story, and 2 Christmases have passed, she would have to be 18. Why was yayoi still concerned about how far she went with her

 

[Omega_Keiichi]

To answer the question above for those that are curious without @ ing them, the age of adulthood in Japan was 20 at the time of publishing. There's some room to discuss the age of consent, but Yayoi is just playing it safe until she is legally an adult.