Pandora Hearts

The genre is dark fantasy and mystery. Here's a rough synopsis: On his 15th birthday, Oz Vessalius is declared guilty by the Baskerville family during his coming-of-age ceremony and falls into the Abyss, a world separate from reality. There, Oz makes a contract with the blood-soaked black rabbit, Alice, and succeeds in returning to his original world. He then struggles to uncover the truth about his sins while helping Alice regain her memories. I copied this from Namu Wiki. It has a bit of an 'Alice in Wonderland' vibe and is a complete series of 24 volumes. The story gets increasingly interesting with twists and turns as it progresses! My friend's favorite character died, so I could press their 'cry button' lol. It was so fun teasing them every time! ㅋㅋ But... my favorite character died too, so I'm a little sad ㅠㅠ (For reference, it's available on KakaoPage with the 'wait for free' system. I started reading it there too, but ended up buying the entire physical manga series.)