Time Out says
Inside the Japanese garden of Shinjuku Gyoen, you'll find this relaxed tea house where the only item on the menu is 'Powdered green tea (with seasonal Japanese confectionery)' for ¥700. You can't get more authentic than that. Look out for the irregular holidays.
11 Naitomachi, Shinjuku-ku
|Transport:||Shinjuku-Gyoenmae Station (Marunouchi line), exit 1; Shinjuku-Sanchome Station (Marunouchi, Fukutoshin, Shinjuku lines)|