Incantation of Resurrection (or the variant of) appears several times:
- ちよた にけら はとほ らすて のはて きらと なりは してと
- ちよた にけら はとほ らすてろ
The first variant appeared twice in episode 2
- Recited by Mai in stair-climbing game.
- Later Mai tried to enter that phrase in her game - only to be notified it was invalid.
The second variant can be heard in the song Sucharaka San-nin Shuu.
It's a reference to Dragon Quest 1, which in Japan used passwords rather than save games.
Stair Climbing Game
Lyrics for The Incantion Of Resurrection