While buying a CD, Tsuna runs into Haru and ends up going shopping with her for some cake for her monthly Haru appreciation day. As the two enter the cake store, Tsuna spots Kyoko and tries to leave before she spots him with Haru and think that they have a relationship. However, Kyoko spots Tsuna and starts to explain that she only eats cake once a month. As Haru and Kyoko introduce themselves to each other, they realize that they have a lot in common and, with the urging of Reborn, decide to head to Tsuna's house to eat their cake.
As the group arrives at Tsuna's house, they start to eat the cakes along with I-Pin and Lambo. I-Pin initially likes Kyoko and Haru for giving her cake and gives them some of her dumpling buns as tokens of her gratitude. After biting into their buns, the two girls collapses since I-Pin forgot that the buns are a type of poison cooking that is only edible to Gyoza-Kempo users. However, I-Pin has the antidote but its enough for only one, forcing Tsuna to pick who to save. Since Tsuna is not able to pick one of the two, Reborn decides to bet their lives with the Dying Will Bullet and shoots the two.
As the group waits for something to happen, Kyoko and Haru are reborn and leave immediately with Tsuna, Reborn and I-Pin following. The two head to the cake shop and start to eat some of the cake forcing Reborn to use his Reverse One Ton Hammer to force the dying will to be extinguished and knocking the girls unconscious. Tsuna is forced to work in order to pay for the cakes that the girls ate.
Later that night, the girls weigh themselves and see that they gained weight, causing their plans for next months appreciation day to be cancelled.
Note: Bold + Italicized = First Appearance