江户深川蛤町有一条店铺林立的道路，稍往里走可以看到围井而建的长屋，这是店家们的居所。一名年轻的旅者来到井边取水，他将水一口气饮干，还闭上眼睛细细回味。他名叫永吉（内野圣阳饰），在京都的豆腐店学成手艺后来到江户闯荡。井水的甘美让永吉赞叹不已，他决定在这里开一家自己的豆腐店。木桶店的姑娘阿文（中谷美纪饰）巧遇这个新来乍到的异乡人，两人一见钟情。

永吉和阿文的豆腐店“京屋”开张了。夫妻俩做的豆腐价廉物美，然而吃惯了江户豆腐的当地人却接受不了柔嫩的京都风味豆腐，因此“京屋”的生意十分惨淡。但永吉夫妇却毫不气馁，竭尽全力推销豆腐。有一位叫作志乃的妇人（岩下志麻饰）一直来“京屋”买豆腐。其实，志乃和丈夫清兵卫（石桥莲司饰）经营着著名的老豆腐店“相州屋”。老夫妻俩的儿子正吉在四岁时走失，从此下落不明。他们把年龄相仿的永吉看成了自己的孩子，并推荐“京屋”代替自家的铺子成了永代寺的专属豆腐供应店。

日月如梭，一晃十八年过去了。永吉和阿文有了三个孩子：长子荣太郎、次子悟郎和女儿希美。在母亲的溺爱下，荣太郎游手好闲，夜夜在外鬼混。这天晚上，荣太郎又去了赌场，输得精光的他将家中那口井的所有权也压上了赌桌。水质纯美的井是豆腐店的生命，平田屋（中村梅雀饰）为了抢到号称“江户第一”的水井压垮京屋故意设计将荣太郎诱入了圈套。

永吉和荣太郎断绝了父子关系，将他逐出了家门。这天，永吉被永代寺的西周（小池荣饰）叫了过去。西周将相州屋的土地权所有书交给了永吉。原来清兵卫曾留下遗言，如果正吉二十年后不回来，就将之传给永吉。走在回家路上的永吉看到一个酷似荣太郎的人影，他拔足追赶，却没有注意到一个武士正骑马分开人群飞驰而来……

A young tofu maker, Eikichi comes from Kyoto to open a tofu shop in a friendly neighborhood. He meets there a feisty local girl Ofumi who befriends him as he sets up his shop, Kyo-ya and in spite of the difficulties stemming from cultural differences between the two ancient capitals including the favored taste of tofu itself, they eventually marry and become the owner of a tofu shop on a more respectable street. Behind the rock-solid business of Kyo-ya, their son, Eitaro bears the brunt of other tofu shops' animosity toward Kyo-ya's refusal to comply with Edo's way of running business and starts to frequent a gambling hall run by the mysterious "Boss", which throws the family into a critical situation that threaten to pull them apart...