Carol B.
Yelp
We stayed at ONE@Tokyo twice during our recent (Oct-Nov 2018) trip to Tokyo. Check-in process was seamless and the front desk attendant was nice and helpful. The "studio" room was definitely the smallest hotel room that I've ever stayed in. My husband and I were both traveling with small rolling suitcases, but there was barely even room to open up even one of them at a time.
The bed was on the stiffer side, which I actually liked. You can manage the thermostat, etc. Modern, but small, bathroom with heated toilet seat, standing shower, sink is in the living area. TV was equipped with Chromecast so we were able to watch Netflix, which was nice. There are also umbrellas in the lobby available to borrow, which definitely came in handy for us.
Room is also equipped with toiletries, hot water kettle, coffee machine, cups, hairdryer, etc. I loved that they give you a little toiletries bag, too. We got vouchers for free coffee. The breakfast buffet is okay. If you're paying for it, I'd say skip it and eat at LIFE (grocery store) or a nearby cafe. Don't miss the rooftop! It offers a beautiful view of Tokyo Skytree.
Overall this place was clean, quiet, and affordable. The location is also great -- less than a 5 minute walk to the subway and about 3 stops away from Tokyo Station. The area itself seems very residential, but Tokyo Skytree has tons of shops, restaurants, etc and there's no shortage of convenience stores and there are a few cute cafes nearby.
We weren't in the room much aside for sleeping, so not a huge deal that the room was tiny. Just beware that if you're traveling with a large suitcase/luggage, it may take up all of the space!