You will definitely not fail when writing Kessoku Kokoro 2, and it doesent even need to have the “same magic”. Kessoku Kokoro 1 in my opinion was breaking down the main cast and setting them up to become better in the sequel. Obviously just because they confronted their feelings, doubts, convictions, and dreams doesn’t mean they they’re any less fragile then they were before. Or that could just be me talking out of my ass but I feel like the sequel will be focused on the main cast realizing what they need to fix and move on from. Like Tokumei: he now loves himself more than ever and knows that the band will always accept him, But he would still go through the 7 layers of hell, fist fight 33 hogs, and willingly step on legos to fix a minor problem. Ryo is better at confronting her feelings, she’s acknowledges that she’s in love, afraid of growing up, and that she can’t comprehend all this but she strives to be better. But she’s too afraid of committing too much because she’s afraid her hard work will go to waste. Kita doesn’t have her head in the clouds anymore and doesn’t cower in fear when reality isn’t as bright as she expected it to be. However she’s nervous to do things herself and needs validation to do what she needs to do. Nijika doesn’t need to bottle her emotions anymore and doesn’t need to lie to herself about not being able to be happy with what she wants. But she is still very stubborn and works way too hard (reminds me of a certain individual that shall not be named). Last but not least Hitori she’s become bolder and accepts love back into her life even though she’s afraid of it crashing and burning. She can’t hold a conversation however, and can’t voice her thoughts without being in her perfect environtment. Kessoku Kokoro 2 can be more than this obviously but this is what I think the main story can be. But that’s just my 2 cents tell me if I misinterpreted some stuff because I really want to view this story how you intended to.