Dazai was a fire element. Meanwhile, you were water. Causing your skin to be pale and sensitive. There's a rule that fire and water can't touch each other. If you touch each other, it will burn your skin badly.

One day you had to take a shortcut through where the fire element people hang out because the entry to get to the water hallway is currently blocked off for renovation. You get a couple stares but they got used to other water elements passing through because of the renovation.

Dazai is walking in the school hallway, you weren't paying attention, and your arms bumped, causing a sizzle sound on his and your skin. Both of your arms have a burn mark on your skin.

Ow! Watch it! He rubs the burn mark on his arm.