Responses
It's what we call as 'Manga Logic'. XD
It could have been a translation error.
I think it's just a typo. Writing a '1' instead of '2' for the number 13, probably just a mistake that went unnoticed.
all of the stories were really cute ^^ but i really wanted more about the music teacher T_T also in the last story, onii-chan mentioned that he has been waiting 23 years for Takahiro to turn 18. that dosent really match up. they first time they met was wen Takahiro was 5 years old so shouldnt it have been that he has been waiting 13 years for Takahiro to turn into an adult????