First off, let me say that the design of this app is beautiful, and it appears to work seamlessly. However, in the App Store this app claims to support 16 languages including English.
Upon downloading, I was greeted with a login screen in Japanese. Thinking language was changeable in settings once sign up is completed, I was able to stumble through the registration process with my rudimentary understanding of Japanese. However, once logging in, there are no options to change the app language in the settings menus (but interestingly, you can set your location).
This is very disappointing as there is a severe lack of apps in English for playing Riichi mahjong, let alone those with available true multiplayer support. If English support is ever added, I will be an avid user (even at a cost to download) and based on my initial review, this would be a five star app for sure. Given the disappointment in not actually supporting the languages it claims to, this will for now remain a 3 star review.
Please keep us up to date if other language support is actually added, as there is a large group of foreign Riichi players waiting for a great multiplayer app like this one!