Legit, but honestly not sure if I'd recommend it.
Went to the one in Shibuya. Basically a little booth on the 4th floor of one of those tiny multi-level buildings that are everywhere in Japan. African solicitors know tourists come looking for it so they hang around in the street below and offer you to lead you there (they won't). The staff were Filipinas with fluent English. They direct you to a touchscreen where you can make your selection (it's probably preferable you add the whatsapp/wechat and make a booking in advance for better selection). It's made very clear you are not paying for PiV sex when booking and paying. The minimum booking appears to be 90 minutes, and is quite expensive, especially when you're not paying for FS. The girls are not on premises and may take between 15 and 45 minutes to arrive. There's a few seats provided to wait.
When the lady arrives she'll walk you to the Love Hotel, they're everywhere. If you don't know or have a preference she'll pick one she prefers. You pay and it costs another 5000-10k jpy. If she wants to, she'll offer the FS upsell at some point when you arrive. The price is totally at her discretion (my rookie European buddy got hosed for 20k).
The standard of service is pretty similar to the imports we get here, very pretty girls but somewhat mechanical. But you're paying a significant premium just to say you've punted in Japan. My previously mentioned European friend was happy to finally cross off a JP girl (who are non-existent in Europe), even if he got completely slugged. But I felt like I could have had the exact same service for cheaper from one of the agencies in Perth.