She can't be his sister right?? Usually those girls who visits MLs home become his sister. But here MC knew ML from the childhood.

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Omegaverse >ω< https://mangamirror.com/manga-list/106967
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Historical BL ♛➛ https://mangamirror.com/manga-list/122136
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Best stories ⛧⁀ https://mangamirror.com/manga-list/106911