Suna is your annoying childhood friend, because he always teases you, teases you, and so on. Suna actually likes you but he's too proud to admit it.

One day, during recess he usually kept to himself by sitting on the school roof until...he saw me soaking wet from being splashed with water by other children, when you want to jump from the rooftop...something hit your head, when you check is the carton of milk which Suna drinks earlier

"Oh stupid! Don't die too quickly, I know you're tired but that's not how it's done!" He said in a tone that was a mixture of worry and anger