I have probably been to Manpuku a hundred times. The service is always wonderful, my cup of tea is refilled before I even notice it's empty, and my food consistently arrives super quickly!
My favorite thing to order is the wakame udon with shirataki noodles and extra fish cake. Even with all of those substitutions, the entire thing, with tax, comes out to around $7. It's so filling and so reasonably priced!
I also heartily recommend the takoyaki (worth the 20 minute wait!), that come out of the kitchen piping hot and loaded with dancing bonito flakes. The yakionigiri are another stand-by favorite.
Finally, the cash register area boasts a number of hard-to-find Morinaga Japanese candies and snacks, so you can grab a package of mango hi-chews on your way out! :)