Thank you.
Didn't know that H-game have that rich lore and main story. Can you tell me more about background of locations? I'm shocked by the dark past of "Research Facility" location
I would not recommend I say too much, except to have a good translation for this game. It took a while to find a decent translation, one of which is in Krongorka's repack of this game.
NoR's locations reveal their lore in journals, dialogue, memories, and descriptions for enemies, weapons, spells, and items. It's not a lot of text but it carries a lot of meaning with context from all the text in the game and logical interpretation. The next darkest location seems to be Ragdum, with a mafia posed against the church using dark magic,
If I had to be brief about notable lore that may not be so obvious, it is that Night of Revenge (AKA a Witch's Night of Revenge) is the spiritual successor of one of D-Lis's previous games, Bullet Requiem. You can see the parallels in the art style of the heroine, though the gameplay is very different because the heroine of Bullet Requiem wielded akimbo pistols with an armament of other firearms as well. A kind of story about beasts and demons was relevant in that game too, although I had a bad translation of the game and do not natively speak Japanese so I can't be sure what was going on in Bullet Requiem.
What I can tell you is some weapons in Night of Revenge originate from weapons in Bullet Requiem canonically. The cannon Aradia can find in the church dungeon is the same cannon the heavy soldiers in the castle used in Bullet Requiem's castle level. The "shotgun" (a spider-web exploding rapier weapon) you can craft from the soul of the Spider Demon is likely a shotgun from the blue gun enemies in the dungeon level of Bullet Requiem. Aradia's starting sword seems similar to the swords wielded by the soldiers in the castle level, at least aesthetically by style though lore-wise possibly not.
For enemies and traps, the big fat undead enemies in the dungeon of Bullet Requiem reflect in their future counterpart the fat prisoner. The mermaid woman in the Unnamed Lake is a setting-appropriate (demon-like) version of the mermaid woman from Bullet Requiem. The aphrodisiac gasses, needles, and pots in Night of Revenge are inspired by the similar effect from the cauldron in Bullet Requiem's library level - which seems similar in nature to the pink clouds floating in the lower levels of the laboratory. The Iron Maiden trap in the dungeons and the spell equivalent Aradia can gain are inspired by similar-looking Iron Maiden traps in Bullet Requiem, though those do not have sexy tentacle flesh and instead simply stabbed with normal spikes as a damage trap. Perhaps most notably, pink flesh and spider people are both from the castle level. The boss of the castle level is a high-ranking priest who got possessed by demonic corruption, transformed into a large flesh enemy, and put down by the heroine of Bullet Requiem. Interestingly, the church has ties to demonic corruption long before witches were involved in the story of Night of Revenge - the heroine of Bullet Requiem was not known to be a witch, only a gunslinger. Alas, if only I knew Japanese or had a good translation of Bullet Requiem.
I will credit D-Lis on having a major improvement in his art style. He also does well in learning new and better game engine implementation. Before he used ClickTeam Pro (an easy-to-use Japanese 2D game engine) for Bullet Requiem, which was good enough but honestly ClickTeam Pro is woefully inadequate for today's standards, merely being an easy vehicle for an artist to turn their art into a playable 2D game. Unity was a vast improvement, but then the Unity license fiasco happened so now D-Lis wants to try Godot. Frankly the work I've seen in Godot is very good, so I have faith D-Lis can make a game at least 75% as technically good as NoR with it. I'm even willing to bet a better game can be made, seeing that there are procedurally generated Super Mario 64 games made in Godot out right now.