I've completed two stays at this convenient and nice property. I'm enrolled in their frequent guest program, although it doesn't seem to be advertised well on their English language website. Aside from a discount on stays and access to day use rates, I don't know what, if any value this membership, or points accumulated in this program have. I guess I'll need to ask the hotel staff the next time I stay there.

Their onsen really is a great place to visit, especially for a day use stay, even if larger rooms are available at hotels in Shinagawa.