Went here with the wife for dinner early on a Tuesday evening, the restaurant was already three quarters full with locals but the owner was friendly and made us feel welcome in his pigeon English. Menu was available in English which was a huge help considering it was a complicated series of set menus available, not really compatible with my phrase book.
Food was great, a number of small courses of very tasty lightly battered tempura cooked right in front of you behind the counter. Ranges from the usual (shrimp) to the strange (fish bone tempura and prawn leg tempura!), all were presented by the chef with advice on how to eat each.
The chef recommended a saki to try and despite finding all sake to taste like hampster wee and turpentine in the past, this was very palatable, notable less strong and more of a subtle flavour. Highly recommend.
Meal was relatively expensive overall coming in at $100 each, but we did have both sake and beer with the meal. Notably more expensive than a lot of the meals we had in Tokyo but very tasty and an enjoyable experience overall. I heartily recommend.
Menu notes that this place has been in hands of the same family (though presumably not in the same location in the concrete building) since 1920 ish. To my mind this is what most tempura restaurants try to emulate.
If you own or manage Tenkane, Shinjuku Odakyu HALC, register now for free tools to enhance your listing, attract new reviews, and respond to reviewers.