Hi, I'm looking for the title of this manga I read not so long ago, impossible to find where I read it, and to remember the title.

It is a yaoi, omegaverse type, love triangle (between an omega, and two alpha brothers). The protagonist is a high school student, omega, who has a boyfriend (alpha) who neglects him. He made a promise with the big brother of the boyfriend in question when they were children to become a fated pair. But the big brother had to leave for certain reasons and left a letter to explain them, and returned several years later to fulfill his promise.

There is a conflict between the two brothers, because the little brother made sure to make the letter disappear but ultimately the protagonism returns to the big brother with whom he made his promise.

Thank you in advance for your replies

In the cage?

Thanks you very much that's it!