Too lazy to translate word by word, so I'll just say what happened.
P1: Next day, anon woke up and find Reimu in good condition, at looked at him as if it was its parents
P2: Anon going to work, so he left a large sum of food for Reimu enough for a day. *facepalm at anon's ignorance at Yu's lack of rationing knowledge*
P3: He come home and find it with an expression that indicates suffering. He think it must be from the overeatting. He also noted the surprisingly low amount of poop in the toilet
P4: Panicked, he went online to look for help and found someone posted that he should massage its backside.
P5: it vomitted paste...
Zidana, you are the resident Chinese translator in OYP right? I'll leave this to you.