Jessica J.
Google
First thing first, for those who has the need to go to toilet often, if you are coming here by joining open trip from Tokyo, then the first thing you can do is go to the toilet first or you will spend your time in waiting line because another participants will go too. They only have 2/3 rooms for female (it should be 2, iirc). After that, you can freely roaming around the lake.
The lake, is the prettiest lake I've ever seen. It looks like a crysta navy blue. I was lucky to experience where the color of the lake and sky were same. I really recommend you to visit this first in the morning. You can find the open trip who puts this location as their first destination of the tour (I used the package tour from Trip, this is not an endorsement).
If you are lucky, you can see swans here! They got one of the prettiest swans I've ever encounter. And if you are lucky again, you can see Mt.Fuji from here too! It was really a wonderful experience.
*the swan cruise looks really elegant but I don't know how to hop inside. But it was unlikely to hop due to tour time limit.