Onsen with bathing suit in Tokyo

Does anyone know of an onsen you can keep bathing suits on? Or has a family room for rent in Tokyo?

Thanks

Asking for an onsen in Japan to be enjoyed in bath suit is a little bit like asking for a swimming pool in the US to be enjoyed naked.

As for private baths, I am afraid I don't know any in the Tokyo area, but there are many of them in nearby Hakone:

http://www.japan-guide.com/e/e5209.html

Thank you for your reply, Uji san. I know it's a weird question. I have no problem being naked in onsen--do I have a choice? It's for my Dad who's never been to Japan and coming to visit me in Tokyo. I was hoping that someone will know some place we can enjoy onsen without being separated.

the Lonely Planet guide book says that Ooedo Onsen Monogatari in Odaiba Tokyo Bay has mixed gender baths where clothing is required. I assume that means bathers or shorts/t-shirts or something similar. www.ooedoonsen.jp 2-57 Aomi Koutou-Ki

No, Oedo Onsen has no baths, where suits are required, except the foot baths. Like other onsen, Oedo Onsen requires you to get naked:
http://www.ooedo-global.jp/english/index.html

There's a great onsen in Chiba. The indoor pools are split up by gender and are naked while the outdoor pools are mixed gender and bathing suits are manditory.
the website is in Japanese
www.yumegurimangekyo.com
hope this is helpful

There is an Onsen named "Seta Onsen, Sanga-no-Yu" at Futako Tamagawaen, Setagaya ku.

This Onsen is an ordinary one (the bath is separated for Male and Female), but also has an open-air bath that requires you to put the swim suit on, and you can be together at there. And they have Family rooms too.

But I can not recommend this Onsen strongly because it costs little bit too expensive at there, so please visit and check their homepage.

http://www.setaonsen.co.jp/english/index.html

I hope this information helps you.