Its pretty good but I would need to see more to have a proper opinion. Meanwhile the word spam gives more exposure, you still need a decent amount of real content to hook people in.

Ohh you sweet summer child...

This entire adding and deleting chapters messes up the fanfic in the library, I had to re-add this fanfic like 3 times already by manually removing it finding it again and re-adding. I'm not sure how many readers might be "lost" because of this but it might be better to have announcement's and such packaged with chapters so it doesn't have to be deleted, bugging out the library.

Meanwhile I love Danmachi as a setting considering how much of the DxD story was covered in almost 50 chapters, having the same amount for Danmachi is not much, unless the story speeds up in a major way thats like very early Danmachi story without giving the characters a lot of time to shine. The setting also has much more characters to cover compared to DxD where the story only focuses on Rias's peerage and the mc.

+1 Considering he grow in power pretty fast and it would make no sense to visit this setting later while it could be a nice way to get more experience for the mc.

Giving them Vitality rings right after he was having trouble "defeating" them... truly just digging himself deeper.

+1

There is no example for it to naturally happen, but there were cases where sacred gears which can move from their host to a new one at their own will moved to a host already having an SG so making them having two at once. Saji also had all Vritra gears collected making him technically have 4 at once.

If you feel its too fast then start stockpiling some chapters, consistency is great anyway and it will also give you some buffer to see people's reactions for where the story is going. Just be careful to not burn yourself out as there are a lot of stories which get out like 50 chapters super fast then slow down to a snail pace only having very short chapters full of filler with the story going nowhere.

+1

This chapter was a pretty pointless filler, its already established he has smut of all characters who have the diary. There is no point randomly describing one, even if this will affect the story the same could have been achieved with like 2 lines telling the reader Hancock is reading Arton's work about her.

The mc would be running on an infinite money cheat pretty much. And with the system it would also translate to xp and power.

Meanwhile its logical from a story standpoint it could get awkward. Rias is filthy rich, that means the mc will have access to unlimited resources with the exception of extremely rare stuff owned by only gods and such. Rias also dotes on her peerage (and the Gremory family too) which means they would also hand out everything for free to him especially since they would benefit from the end products. And considering how highly valued something like healing potions or fertility potions would be, the devils throttling him for money would be very unrealistic if he ever joined.

The overall story is really great but all the lewd scenes and filler together stretch it too much.

I'm not trying to bash the MC but he should really accept whatever those pheromones do are a form of mind control, just a really hard to detect one. Its not even subtle considering he practically "marry" a women every day, usually only in a few hours of interaction. I could even accept the first case with Rias who was in an emotional turmoil to get attached to some sort of love at first sight, but with Sona going into the conversation with "It's impossible an entire peerage married you without mind control in like a week" an then proceeds to marry him herself after a few hours is just insane and straight up impossible without affecting her mind and free will. His pheromones are practically drugging every girl he wants with some sort of love potion effect, which is just mind control via chemicals.

Considering his previous life experiences the mc is pretty gullible/naive. Considering he is also knowledgeable with the HP universe he should know its pretty easy to check the wand's usage history, read memories, etc... Overall its much harder to get away with crimes when magic involved. He is taking far too much risk for what can be considered pocket money. He could simply wait to get into Hogwarts and repair/grab all the junk in the Room of Requirements to make much more he could ever peddle as kid on carpet repairing watches and cauldrons. I'm pretty sure he could make more by going to a mundane junkyard/pawn shop, buying broken stuff legally and repair them, considering how proud his mom were I'm pretty sure she would even help. Getting into the entire swapping parts in stuff and making a cut on the stolen parts is just far too much risk for barely any money considering they also have to spend on fake parts.

Can he downcast cursed flames on a lower level? In its current form I'm pretty sure its not worth to spend 3.2 times energy for 1.6 times damage even with the extra "debuff" chance and bounce.

I quite like the story but in my opinion there is a little bit too much "banter", most of the chapter felt like a strange slapstick comedy episode which is kind of out of place, especially with the topic being pretty serious. If that's what you are going for then I guess its fine, but I'm getting that "I'm so random" vibe too much for my taste.

To be honest it feels like a strange timeskip, but in this case you skipped the good part.

This might be the most convenient reason for a harem I have ever read which is both amusing and impressive.