I think the 'Baby Finches' Happy Event is what inspired the "Sensei suicide led to Maya praying and this was the result" theory.
At the end of that event, Sensei breaks his neck while Maya begs him not to:
This on top of Maya apparently wishing for something:
And according to Yasu, having a god at her shrine:
And Maya Prime apparently being convinced Sensei was born again:
Makes it seem like she's directly involved. According to Pareidolia, the gods also gave him his body:
Which could explain his magic ever growing penis and suspiciously muscular body.
It was Rin in her Chapter 2 'The Art of Never Knowing' Event. Same one where it's revealed that Rin was adopted.