Theres a manga where the main character has been enrolled in a a school for a long time but because of his family thinking of him as noithing they have prevented him from advancing. The school is like a battle school where people fight for advancement and have a lot of different powers. He's a "failure" since he has only basic powers but he's strong enough to be some of the most powerful student in the school.

Oh yeah and he starts living with the idol of the school and his bro-con sister shows up as well....

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Rakudai Kishi no Eiyuutan

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That's the one thanks

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