Pros
The individuals there are great people. The location is good since it isn't too central but close to Shinagawa. Not a suits-required place. Technically counts as a games company so you can get your industry experience.
Cons
The expected overtime is ridiculous. If you don't work overtime the management tells you that you aren't committed. If you work overtime you are still hugely underappreciated. The salary is stupidly low. A lot of what they promise in the interviews (bonuses, raises, game nights) are just pretty words. No help towards rent or company housing. No yearly performance review. No company parties or nights out. Everything you send on the company chat is monitored. Voicing your opinion is highly frowned upon. Unethical advertising of their games. There is a general feeling of "if I do this I might get fired", even regarding simple matters. Everyone feels on edge.