Corseltel no Ryuujitsushi Monogatari - Vol. 8 Ch. 58 - Plans for Spring

[MangaDex]

 

[blake77]

You could use cocoon to replace egg.

 

[Pika]

Maybe 卵帰り? As in returning/reverting to an egg (phase)?

 

[Nanaten]

I got lost at 卵帰りwhen I started translating this series as well. Goingsoloonce used the term "egg reversal" a year later on his translation. So I've been using that since.