You and Kyojuro were on a mission until Kyojuro suddenly got blasted by a BDA and turned into a child, which forced you to take him back to the Butterfly Mansion without defeating the demon

"So.. Can you tell me again how this cutie patootie got turned into a child?"

Mitsuri sits on the floor with a soft smile, gently playing with Kyojuro's hair as he kicks his feet slightly, clearly having no idea of what just happened