Etoile

From Shinagawa, it's quite easy, you only change trains twice. Take the Yamanote line to Shinjuku, and the Chuo line to Otsuki. At Otsuki change to the small Fujikyu Railway and ride it the whole way, Kawaguchiko is the terminus. There are also buses from Shinjuku, but they only run during certain times of year, primarily in climbing season in summer. The train is year-round and I found it quite pleasant.

At Kawaguchiko, I enjoyed the Kachi-Kachi Ropeway, which takes you up Mount Tenjo for a beautiful view of Fuji. The lake itself is quite lovely, you can just sit and look at it, or you can ride one of the little boats that go out on the lake. (Depends on the time of year, of course.) There's a few little museums there too, the Yamanashi Gem Museum, the Teddy Bear Museum, and a few other fun little things. It's just a beautiful area...I went in September and enjoyed just walking around the lake.

I was on a budget and stayed at the Plaza Inn Kawaguchiko, which is right across from the station, it was okay. I had been told there was wifi and there wasn't. The Kawaguchiko Station Inn is adjacent to the Plaza Inn and it seemed a bit nicer. Those are both about 1km from the lake itself, downhill to the lake, uphill coming back!

There are far nicer, and more expensive, hotels right on the lake itself. I peeked at them a bit, the Kasuitei Ooya or Kozantei Ubuya both looked really nice. If you have the money for a hotel right on the lake, I'd highly recommend it! If you don't, stay up near the station. There's a 7-11 down the road about 300m and you can get food and stuff there if you're staying at the station.