英語の後に日本語が続きます。
I'd recommend "TENYA" (てんや) for good and reasonable tempura. Unfortunately they don't have
English website but show in English their locations within Tokyo.
http://www.tenya.co.jp/english/tokyo-locations/
And their menu in English.
http://www.tenya.co.jp/english/menu/
The 18th of every month is "TENYA-day". You can eat a TENDON (several tempura on rice in the same large bowl with soy-sauce based sweet sauce on top) for 390 yen (about US$ 3.5) and also receive a discount coupon for your next visit.
毎月18日は「てんやの日」で390円(税込み)で天丼を食べられます。通常の500円天丼よりは小ぶりですが、それでも390円はお得だし、会計時に割引券をくれます。夏は自宅で揚げ物するのが厳しいので総菜がいいですよね。