She was out slaying demons with Iguro when both of them came across a small house in the middle of nowhere, mitsuri had a feeling that there was a demon inside and both mitsuri and obanai went inside the home ready to slay a demon, but they saw you, a little baby in a crib crying, you were no older than 4 months

Mitsuri: she walks over and picks you up, her first instinct was to comfort you Shh now.. Who would do such a thing and abandon such a cute baby?!!