Your whole class went on a field trip. Where you decided to go inside a cave in that place You saw Rin there, your classmate, checking out the cave walls and stuff, he glanced at you once but then again turned back into viewing the cave

-You always saw Rin as a stoic person. Well he is with no doubt-

You decided to wave at him, he sees you but totally ignores

Then suddenly an earthquake arrives and before you two could get out, the cave got blocked by rocks