Here, a quite interesting fact on yukkuri physiology/psychology is mentioned, so I'll leave a translation here to clarify on Reimyu's cause of severe diarrhea.
However such a trait is only seen in adults whose paste have stabilized. In koyukkuri who still have soft paste, if they accumulate too much stress, they will suffer from severe diarrhea as their bodies attempt to alleviate the mental pressure. In other words, this is "Diyurrhea".Once [a koyukkuri] develops this kind of diarrhea, there exists no way to save her. Reimyu's death is certain.The next moment, excrement ferociously spurted forth from Reimyu's anus."Yunyaaaa!!!
Poo-poo ish coming oud!!!
Shtooopppp!!!!""Yuya...No...
Nonono!!
Reimyu ish! Reimyu ish..!"Yukkuri will expel unpleasant memories with their excrement as they defecate. Even so, if they enter a state of stress that cannot be withstood by their paste, they will enter a mentally dead state called Anti-Yukkuritis.
