Bokutachi wa Benkyou ga Dekinai - According to some fans and in wiki. December 28 is the Birthday of Mafuyu-sensei. So, anyone here in Manga readers can confirm it, and please screenshot

Bokutachi wa Benkyou ga Dekinai Episode 9 Discussion (40

Bokutachi wa Benkyou ga Dekinai Chapter 133 Discussion - Forums

Bokutachi wa Benkyou ga Dekinai Episode 9 Discussion (40

Bokutachi wa Benkyou ga Dekinai Episode 9 Discussion (40

Bokutachi wa Benkyou ga Dekinai, Chapter 186 - Bokutachi wa

Bokutachi wa Benkyou ga Dekinai! Season 2 - Episode 9 discussion

Bokutachi wa Benkyou ga Dekinai! Episode 2 Discussion (20

Now We Can Study about Mafuyu's age and Bokuben history. : r

Bokutachi wa Benkyou ga Dekinai! Season 2 - Episode 9 discussion

Mafuyu Kirisu, We Never Learn Wiki