Rakkan opened in Roppongi a few years back, and immediately became a hit. Lines out the door, and closing hours that were simply "when the soup runs out". The shop was closed every time I tried to go.
Then, in a strange move, they shut down and moved to Tachikawa, about an hour out of central Tokyo.
Then, in another strange move, they opened a 2nd shop in Musashi-Koyama, an unlikely suburb of the big city. As Musashi-Koyama is much closer, a quick trip was in order.
I can see why this one was popular. Simple shoyu, hit with niboshi, and topped with a mass of diced onion. This is Hachioji-style done perfectly.
The shio with olive oil also looked excellent.
Official Site Here
Tokyo, Meguro-ku, Megurohoncho 3-3-12
Closest station: Musashi-Koyama
Open 11:00-15:00, 17:00-21:00