This is a very large venue that holds between 2,000-3,000 people and is where much more famous acts play in Osaka. The live room is huge which a large stage. The venue has escalators and elevators as well. Once you pay to get into the venue everything is on the same level and there are ramps inside the venue. There is a very nice map on the website that shows you all of the accessibility features of the venue.
The bathroom has stalls and western-style toilets. I am not sure how many toilets, but there are definitely more than one. I cannot recall the size of the bathroom, but it is a nice size. The bathroom is outside of the venue so you have to walk a bit to get there, but do not need to deal with any steps.
apan 〒556-0017 Osaka Prefecture, Osaka, Naniwa Ward, Minatomachi, 1 Chome−3−1, Mitomachi River Place