Read manga: Tsubame-chan Chi no Kateinai Renai

manga
Summary:

For the second son Takeda Yoh, love is to be able to choose "the one" who stands above all others, to choose the her who is the most precious to him, and the her who he wants to protect the most. He found love in Tsubame, an adopted sister, and everything was fine...
...until his two brothers confessed their feelings to Tsubame. It's time for her to make her choice. Who will be her precious "one"?

"The only person who I can give happiness to... The only person who I like is..."