I've been going here for aeons (back in the 90s) when their tofu donburi was only 10 bucks! It's a bit more expensive now but I think it's purely inflation adjusted. I still come here for the donburi and haven't really had anything else. A big simple bowl of rice with stuff on top (they have good vegetarian options esp. the tofu donburi) and a green tea. Done and done.
Plus the space is cosy, the front sign hasn't changed in a long time (a comforting sight), and it's located on Baldwin Street which is one of the best hidden local spots to find lots of good food on one tiny street away from the traffic.