OMORI: Not a Perfect Sister

After Mari gets too carried on her daily matters and preparation for college, she lets everything go, except for her little brother Sunny, realising she's been on the verge of forgetting how much he means to her and what he's been through, and deciding to show all her concerns about him.
Has she been not the sister Sunny wanted her to be? What did she have to go through to prove worth?..

"My thoughts will follow into your dreams." ⚘
Note: None of the art included is mine. I will give references to them at the end of a chapter.
Note: The events differ from those of the original OMORI. The story is partly inspired by OMARI AU (I don't entirely know it.)
Note: This is INCOMPLETE yet.
Cover: https://pin.it/5k2WArj (edited).