Thank you for this thoughtful review. In fact, I love reading long feedback so no need to apologize for it! Usually, I don't get to hear live feedback from players. By the time they finish the game, they've forgotten most of their reactions on events and scenes.
I'm happy to hear that you enjoyed all storylines. Each was created with a distinctive style for different preferences. The stories are obviously focused on the main characters so there is a lot missing about the supporting roles.
1. I regret not revealing not enough of Rasumi because so far she seems to be a black sheep despite her various roles. She is not the main villain in some routes, like she didn't cause the tragedy in Junoru's story. In Sachiro's route, she acts as a supporting character. Without Rasumi's help, Sachiro wouldn't be able to ever meet MC normally. In the bonus scenes there is a small dialogue between Kaichi and Rasumi. I left it as an open end, because these two have a seperate background story. Rasumi double-faced nature started since her traumatic childhood. A short scene is revealed in her diary during Kurato's route chapter 4. Another hint was left when Blace said Jace and Rasumi have a bad relationship. Jace is the guardian of Heaven's gate and Rasumi is an angel- which means they had some encounters before. The first time Rasumi meets MC, she acts very friendly. I had this idea that Rasumi watched MC from the heavens, thus knowing MC for a long time. If I ever get the chance to expand the lore, I'd love to write more about this character! I've created her long before Dark Nights existed so my mind is full of ideas.
2. Chain is also one of my personal favorites- the mysterious one. Just like Rasumi, I didn't reveal much about his background. Although, he is way more popular. The first encounter of Ikuya with Chain is that she walked away , scared. Their chemistry will be a funny or interesting development. His relationship with the MC varies a lot depending on which route you are. To reassure you, Chain is completely human. If he were super natural, he might dislike himself too(?) which sounds edgy. So far there were hints that Chain lives alone. His place has no any hints related to his friends and family. He met Kurato since he was a teen at the investigator department. He might have been working there longer. The woman in Junoru's route was one of Chain's ancestors since she looks like Chain. They practise hunting supernaturals for generations, but now there are none of those specialists left. It was mentioned somewhere Chain killed a cousin who turned into a vampire. Roya recognizes Chain because of his bloodline. Aside that, Roya encountered him a several times before. The "hunters" are known for their skillful and terrific tactics of capturing/killing supernaturals. There is a black market for these kinds, hence Roya is afraid of ending up there. If I would explore more of this world if I were to write Chain's story.
3. Arount the time Roya attacked the teacher, he already drunk one of those potions. His parents didn't know this. The school ghost was killed by other classmates and Roya has nothing to do with that. He tends to mess around with Kurato. Not all characters speak the truth at times. Kurato used to have a very low self-esteem which made him an easy target. Usually bullies aren't aware of the damage they cause. The teasing starts innocently and gradually gets worse. Roya didn't have any friends during his childhood, and still doesn't in present time. He has trust issues because of the events that happened in the past (kidnapping, conflicts with villagers, murder of parents, betrayal of aquaintances etc.) He doesn't look down on other people, like he saw some potention in MC, but prefers to keep emotional distance. The interactions with his parents were shown from Junoru's perspective. Junoru once mentioned that Roya, despite being older, wasn't a suitable heir because of his troublesome personality. He is mischievous in nature and naturally smart but doesn't put much of his talents to use.
I thought that I covered enough of his backstory, but I realized that it was mostly told from other character's perspectives. Roya is a complex character because he acts as he feels like in the moment. I actually had him in mind as 5th romance-able, but 5 storylines felt way too much.
The flirty arch-type might be the least likeable so I removed him. Now he is a side character somehow a lot people got their eyes on him lol.
4. There is a time skip from where the twins were forced to kill and present time where they work for themselves. I had a seperate story in mind of how they came to be- and it's pretty dark. The people who wanted to kill the Kenriji captured the twins to work for them. Luckily it didn't last long because the twins managed to escape a short while after the Kenriji were dead. They didn't appear in Sachiro and Zeikun's storylines because they are different creatures. The twin's main focus are humans/undead and those that jump through time by accident (Kurato). Unlike Chain, they completely unaffiliated. They act to what they think is right to keep the world's balance even if it needs sacrifices (Junoru's route). Jace tends to show less empathy as he is used to sending people to the Heaven. Blace has dealt with different tasks and sometimes hesitates to make decisions.
About the main characters, each has a distinctive personality. I had different editors and proof readers working on each route. Because of this, the MC might feel inconsistent. Although, in real life people tend to act differently in each relationship too. I'm glad to know that at least one of the main characters stole your heart<3 It's such a coincidence that we have similar elements in our stories. Sachiro was quite difficult to write, because I had no main goal for him in mind for a while. I re-wrote his story a several times before I came to this point. One of the major changes was adding his adult form. From there the rest became easy to direct his story.
Thank you for the praises on my style! I especially developed it for creating this visual novel. To be honest, I tried stepping away a bit from anime style because it wasn't perceived positively by people around me. I choose to focus on composition and colors as keypoints (I struggled with artblock and identity for a several years. Because of this, Dark Nights got affected by delay in development). After I finished all CG art, I added a lot of cutscenes and small animations. For Zeikun's route, I wanted the scenes in inkwash style. His themes are around oriental cultures, so I thought that was the most fitting. In Junoru's storyline, a lot cutscenes were more like graphic design and "straight-cut". Sachiro's route should had more sketchy drawn scenes. It reflects his dreams but also uncentainty. For Kurato, it was a combination of all. During the last years of developemt, I wanted to experiment with visuals and it shows there.
All of the side characters have their own lore. I created this visual novel because I love my OCs and wanted to flesh out their stories. Even if I don't create visuals novels for them again, you'll see/read more about them in other forms (illustrations, comic, animation etc). In the bonus scenes I added dialogues that couldn't find a place in the main story.
Dark Nights is my very first published writing and I'm happy to receive so many positive feedback (´･ᴗ･ ` ) Anyway, thank you for your time playing and sharing your thoughts!