Doubts on Love Hotels

I am planning a one day Stay at a love hotel in Tokyo/Osaka during our trip in April.

Although I've searched a lot about it, I can't really find much about how to book exact rooms. I understand that we can just go in person check in at that day itself. But we don't want to risk not getting a room.

So, I browsed Agoda/Booking.com for these hotels. But the photos of these hotels are just normal room with bed and bathroom. None of the theme/lighting photos are included in these.

How do I book these themed love hotel rooms in advance online? Can I do it online?

Or do the digital check-in board have options to select the room we want after booking a generic room online?

If someone with prior experience/local/knowledge on this could share your thoughts. It'd be helpful.

Thanks in advance.