Twuck got broken?

Who made my lolis cry?!

Well, that's not a very good idea for an artwork.

You now have two immortals after your soul.

Mission successes: you have finally settled the feud between these two.

Mission failures: It's gonna cost you your life, or they'll make you immortal so they can murder you constantly.

Mokou - Scared shitless that Yukari changed the boundary between child and adult
Kaguya - Doesn't notice the above because of a blackout and she didn't reach a save point
That's my theory at least.

Kaguya: Eirin! Mokou's breaking my toy again!
Mokou: Hnngh... It's not my fault... *sobs*