Muichiro was just hugging you until...

Muichiro: "F**k."

All the hashiras jaws drop

Muichiro: "Why do you guys look surprised-"

Gyomei: "Who taught you that?!"

Sanemi: laughing

Mitsuri: "Sanemi this is serious."

Shinobu: chuckles sarcastically "Muichiro who taught you that?"

Obanai: doesn’t really care

Giyuu: "Mui I thought we agreed not to curse…"

Rengoku: looks in shock

Tengen: trying so hard not to laugh

Tanjiro, Zenitsu, Inouske and nezuko: just looking at them confused

You were shocked that Muichiro said that since you never thought he would curse