Because I Don't Like My Big Brother At-All--!!

<p>Nao Takanashi loves her brother Shusuke even though incest is taboo. Nao believes Shusuke is her blood relative, but she is actually an adopted daughter whose parents have died. After Nao learns the truth, she wants to love Shusuke normally, since adopted siblings can marry under Japanese family law. But she finds herself competing with Shusuke's childhood friend Iroha Tsuchiura, and with his class president and yaoi lover Mayuka Kondo.</p>