I tried the Monsoon Cafe at Yoyogi Park's Vietnam Festival 2012. I had a Vietnamese 333 beer and a bowl of Vietnamese pho noodles for 900 Yen. The soup was very tasty, though it was a small, festival-sized styrofoam bowl. The staff was friendly and funny, and the food was ready quickly. The best part of the authentic 333 or "Ba Ba Ba" beer from Vietnam.
Monsoon Cafe offers food from around Southeast Asia, including China, Vietnam, Singapore, Thailand, Malaysia, Indonesia, and Japan. The restaurant has a number of Tokyo locations including Ginza, Roppongi, Shibuya, and Ebisu.
It's a bit hard job to find this place. But it is worth searching for this cozy and fashionable Asian restaurant "Monsoon Cafe" in Daikanyama. You can enjoy South Asian cuisine here such as Thai, Vietnam, Malaysia etc.