"If I have to be bitten, I want it to be you." This is a story about an unfriendly, masculine, hot alpha and an idol who changed from a beta to an omega, moving in together due to an agreement.

"Why do you think I've been protecting your nape all along?" Yasaki, a newbie idol, is a former beta. He lived a completely normal high school life until one day he changed suddenly from a beta to an omega negative. He's been having his friend Kurokawa, an alpha, mark him regularly ever since he changed and was attacked on campus. It's been two years since they began living together with the deal that they'll stop when they find significant others. Yasaki is completely used to this lifestyle now, but recently Kurokawa's marking has gotten gradually more and more intense!