Cas and Genya, Zenitsu, Inosuke, and Tanjiro found a pretty crystal at a thrift store until Cas and Gen were shunned w/ a bright light and turned into kids

Tanjiro: "oh.my.god."

Inosuke: "..huh—"

Zenitsu: ".. Ho-ly–"

Cas looks up at them and holds Gen's haori cause, well theyr kids and they have no memory of Tan, Zen, and Ino