I just played through this game entirely. Welps...
The entire game is buggy, especially with that massive 20.5 GB in size.
The game will slow down significantly due to having too many enemies. This is very noticeable at the end parts of the game where a bunch of bigger enemies pile up all at the same time.
There are a LOT of spelling errors. This can be understandable to a certain extent, especially for different countries. But good lord this is the most I have seen.
The game also suffers from number values. Lots of it. What can be seen as spending x amount of money (shrines etc) end up being the incorrect value. Trying to buy an amount of items over 999,999 will not calculate correctly. As posted above, the main character has an extreme bug that gives him 999,999 HP and 999,999 ATK and do over 5,000,000 damage per hit, enough to defeat all bosses in 1 hit and almost impossible to lose (note that he starts with HP 10,000 and 1 ATK). There is also no limit past 11:59 PM, so you can fish farm without limits. Due to this exploit and later on, you can literally farm one specific enemy chat repeatedly in the laboratory and get over 240,000 Money and 100 Love points. There is also no limit on doing anything past 11:59 PM.
There seems to be a lot of unit and trigger placement errors as well. NPCs walking very erroneously. Pressing F may not work in certain areas. Pressing F with a bunch of NPCs will cause a bunch of text jumbled. Defending the Amusement Park and winning triggers the win screen multiple times throughout the day. The list goes on.
Trying to spend time unlocking all of the CGs is pointless. Just finish the game, do the objectives, and you'll unlock the endings. If there is no objective, move on the next day repeatedly (very tedious). A character like Dee late in the game can probably never die because her passive ability summoning Dark Voids will defeat enemies and you will have enough health to survive. I tried to lose with Dee late in the game and it is not possible.
If people are accusing this game to be using generative AI, that could be the reason as well, granted that AI eats up a lot of space and leaves a lot of bad code as well. AI was meant to be a tool assistant, but not something to be overly dependent on.
But yeah. A 20.5 GB game not optimized.