[From DMP]:

Katsura, a second year in his high school's archery club, has a hard time controlling his nerves. His "secret weapon" is his brother's best friend and childhood buddy, Sou! One hug from Sou and Katsura's nerves are soothed to a peaceful calm. But he can't keep Sou around him forever. As he wonders how he'll survive without Sou's hugs, his friend Kouichi suddenly asks if he can be the one to save him, and kisses him! What now?!

Two families are tied together by a curse. Every 100 years, one person from each family must share the same fate for exactly one year. The pair will be subjected to 12 misfortunes where one will get hurt while the other must sustain their injuries in return.

When Kagura Ikumi was 7, his parents died in an accident. Since then, he has been living an ordinary life. Until the day of his 17th birthday where he meets a mysterious transfer student, Ichijyou Chihaya. However, this fateful encounter between them is only the start of their intertwined fate. For the next year, the two of them will be forced to face 12 misfortunes on the 13th of every month, a curse that has never left any previous pair alive.

[From DMP]:

At Wataru Fujii's high school, it's all the rage to wear paired rings with the girl you love. Wataru wears one though he is single, and one day inadvertently discovers that his ring pairs up with that of tall, handsome and smart Yuichi Kazuki, the senior classman idolized by the entire school. Though Kazuki has a reputation for being kind to all, when dealing with Wataru, he is strangely harsh. Their paired rings somehow draw them together and the two alternately clash and attract, as they must sort out their budding feelings for each other.

Although only 19 years old, using his good looks and his body as a weapon, Kanzaki Nao is a natural gigolo. Being stabbed after a breakup, he is saved by a refined and dangerous man who is a Yakuza -- Murou Ryouichi, boss of the Ichinose-group. Stopping Nao from leaving the city after his wounds have healed, Murou brings him to his apartment and offers him a deal in order to pay for Nao’s treatment.

Even though Murou tells him that he’s “not interested in brats”, he’s contradicting his words when he starts kissing Nao like a lover. What will happen to Nao who swears by himself that he definitely won’t fall in love.....?