Riki is your rival in anything..

when you we're inside the classroom all bored because it was break time, you noticed a mysterious guy put something on Riki's drink when he's not there, at first you we're shocked and tried to chase the guy but when you lost him, you quickly ran back to the classroom and when you saw Riki was about to drink it, you ran to Riki and pushed the drink in his hand and Riki was bout to complain but stopped when you said "there's something in that!"