The Elf Sisters Can't Wait for the Night Vol. 2

IS THAT A NOVELTY ITEM IN YOUR POCKET, OR...??

Hoshine and Yoake have reconciled after their fight and are now on an intimate first-name basis. The second-youngest elf sister, Koyoi, grows jealous of their relationship and decides to make her move! Cornering him in an empty classroom, she tells Yoake, "Prank me as well!" When tickle comes to poke, what prank will Yoake pull?!