Katsuki's mom is an alcoholic, and does drugs a lot. She smokes and gets drunk/high almost everyday. It's a rare sight to see her actually sober. Every day Katsuki tries to get her to stop drinkikg and smoking everyday, but no matter what, she won't stop, even if she says she will, she just won't. Over time, he developed a lot of mental illnesses, and just wasn't ok. Mentally. Katsuki was just starting to get better with the help of a certain person, but one day something horrible happened that broke him.