JR Kawasaki station is on the Tokaido Main Line from Tokyo. The immediately adjacent Keikyu Kawasaki station is also accessible more cheaply on the private Keihin line from Shinagawa.
The surprisingly rustic Kawasaki Daishi Line (川崎大師線) putters through people's backyards, and is useful for the three-stop trip from Keikyu Kawasaki to Kawasaki Daishi. The total fare from Shinagawa is only about ¥300.
The Legend of Kanamara-sama
Once upon a time, but in a land not very far away if you happen to live in Tokyo, there lived a beautiful princess. (Well, actually she was an innkeeper's daughter, but close enough.) But alas, an evil demon with sharp teeth had taken a liking to her. The demon had courted the girl, but she had stayed pure, and one day the demon learned that the girl was engaged to be married the very next day. So that night, the demon snuck into her house and crawled right up inside her! Our heroine, terrified but helpless, told no-one and the marriage ceremony went ahead as planned... but on the night of the wedding, when her new husband tried to perform his conjugal duties for the first time, the demon's sharp teeth went snickety-snack! and the poor man was turned into a eunuch. And the tale tells us that her next husband met the same fate, although the details of how they conned the village idiot into marrying her have not passed down to us.
It was clear that things could not go on like this, and the whole village met to discuss the, shall we say, prickly issue. After extensive deliberations, a candle lit up over the blacksmith's head: "Why not," he said, "why not deflower the girl with an iron phallus?" The metal tool was duly made and tested, and upon chomping down the demon found that it had bitten off more than it could chew; whimpering, it crawled out and slunk off to hide in a dark corner and nurse its broken teeth. The blacksmith married the girl and they all lived happily ever after... except the demon and the two eunuchs, that is.
Kawasaki is largely an industrial area and residential suburb — as typical in Japan, not much distinction between the two is made. But there's one very large temple and one very offbeat shrine to draw in the occasional curious tourist.
Kawasaki Daishi (川崎大師), officially Heikenji (平間寺).  (in Japanese). A large temple dedicated to Kobo Daishi, a astonishing monk and historical figure (see Mt. Koya). Featuring a 8-sided, 5-storied pagoda and more large temple buildings than you can shake a stick at, Kawasaki Daishi is a textbook example of a Japanese temple and remarkably primarily for the fact that on a weekday you can pretty much have the place to yourself. Easily reached on foot from Kawasaki Daishi station, a 10-minute stroll through a shopping arcade.
Wakamiya Hachiman-gū Shrine (若宮八幡宮). A quiet Shinto shrine that would be indistinguishable from your average neighborhood shrine if not for one thing: this happens to be one of Japan's few remaining fertility shrines, and the deity venerated here assumes the form of a meter-long iron phallus, known as Kanamara-sama (金まら様, lit. "Iron Big Penis Lord"). There are a number of stories behind this, and while the most entertaining one is certainly the official legend (see box), the more likely explanation seems that prostitutes from nearby brothels — still a large industry in Kawasaki — used to pray here for protection. To get to the shrine, take the only exit from Kawasaki Daishi station and turn right, then just walk along the curving road for a block or two and you'll spot the shrine on your right. Definitely best visited during festival time (see Do).
In the shrine building you can also find a small sex museum, showcasing mostly Japanese erotic art. A few notable exhibits include a version of the Three Monkeys with two extra monkeys and life-sized brass model of a vagina; if you buy an amulet from the shop (see Buy), you're supposed to rub it against this. Opening hours are erratic, but the shrine shop attendant will usually be happy to open it up on request. Entry is free, but donations are accepted.
Kawasaki's best-known event is the Kanamara Matsuri (金まら祭り), also known as the Iron Penis Festival, held yearly in early April — check with the Tokyo TIC for exact dates. Penis-laden temple floats (o-mikoshi) are paraded down the streets of Kawasaki and everybody gets sloshed. The festival has been to some extent hijacked by foreign tourists and Tokyo's transvestite ("new half") community, who often make up half the audience, but as you can imagine the people running the show aren't terribly uptight and nobody seems to mind.
Wakamiya Hachiman has a wonderful selection of amulets promising fertility, sexual prowess and protection from disease. Prices ¥500-1000, and some of the revenue goes to HIV/AIDS research.
In festival time, a little market selling penis-shaped candies and other sexual paraphernalia pops up on the shrine grounds.
There is no compelling reason to stay overnight and most visitors daytrip from Tokyo.