'Asta' (as I like to simply call it) - I have no idea of the '3' moniker, or indeed where the first two went - is as genuine a Japanese canteen as you'll find in London. I was lucky enough to, along with a colleague, be taken here on several occasions for a quick lunch by a client (indicative of how welcoming the Japanese are!)
By 'genuine' I mean no dumbed-down menus, no super-slick interiors to detract from potentially average food, and no gimmicks of any kind. The place is staffed and run by Japanese nationals as any self-respecting Japanese restaurant should be - and perhaps more importantly, frequented by them regularly, too. Service is smiling and attentive and no more that it needs to be.
The food is inexpensive (~£6-8 for a bento, £7-11 for ramen, udon or donburi) and so tasty. On my most recent trip I had beef ramen with tan tan (sesame paste) soup base, and my brother had salmon teriyaki on brown rice. Both dishes had generous proportions of meat/fish, and the donburi came with a side salad and pickles.
The unagi (eel) is also lovely, and the place does an extensive line in pick-your-soup base noodle bowl dishes where you have the option of shoyu, miso, and sesame as mentioned above, among others. I can't speak for the takeaway bento, but they looked pretty solid and of a decent quality. Drinks come in the familiar (Coke etc) and the more, um, 'traditional' - aloe vera juice, Pocari, cold bottled green and black teas and others.
This place is rather hidden away on the fringes of the City, behind Aldgate station on the Petticoat Lane side. In many ways it's a great location as it's very much a local haunt, and in others a little frustrating as even if you're working in the City it can be a fair walk to get there and back! My advice would also be to get there early (between midday and half-past) to ensure a seat, as well as before some of the more popular items on the menu disappear.
In brief summary, I couldn't really recommend this place enough if you're in the area. You'll get multi-kudos from any friends Nippon friends (or appreciators of their incredible cuisine) and have a lunch to beat the hell out of an uninspired sandwich / soft-drink combo whilst spending a similarly scant amount of your hard-earned cash.
As your fellow diners would say: "itedakimas!" read more