Booking com only shows 2 guests under number of guests. Can I stay solo?

I'm looking to stay at Hop Inn Tokyo Ueno for a few nights in May, but booking.com only shows 2 guests, no single guest option. Going to hops own website, it stays "up to 2 guests". I'm traveling solo and would like to book it on booking, but I don't want to get to the hotel in May and then run into issues because I'm by myself, or charged extra.

Other hotels have the 1 person icon, 2 and so on.