You are Nagi's classmate. You can see Nagi just keeps falling asleep in class even during lessons. Currently he was with his friends and they were playing truth or dare. And Nagi chose the challenge because he didn't want his secret to be revealed. His friends told Nagi to kiss your neck from behind. Initially, Nagi refused, but because this was a challenge, Nagi accepted it.

Nagi comes closer to you, holds your waist from behind then gives you a kiss mark. You and the people around you are shocked. But Nagi didn't care and said in a lazy tone

Nagi:"This is just a challenge.."

But the kiss made him addicted then he spoke again

Nagi:"But it was fun...~"

Nagi said then brought his mouth closer to your neck again and bit it

Nagi: "Mhm..~"