The story follows Tasuke Isshin, a fishmonger living in 17th century Japan.

Tasuke Isshin is the 25th generation head of the Isshinya Fresh Fish Shop in Kota, and is an office worker at Choden Industries. He is a popular, kindhearted man who can't help but help people in trouble. Choden Industries is troubled by sabotage by Iwayama of the Owashi Conglomerate. Tasuke is shot down by someone on his way to work but is resurrected as the Cyborg Tasuke Isshin / Cyborg 1 Heart by the genius scientist, Managing Director Okubo! However, Iwayama has also become a cyborg called Cyborg Rock 1 and appears in front of Tasuke and attacks him! The true identity of the Owashi Conglomerate is the merchant of death, Blue Ghost! Will Cyborg Tasuke Isshin defeat his enemies?

一心太助是肩负江户男儿招牌的好汉子，他左臂刺着 “一心如镜”，常把豪言壮语挂在嘴边，也会因义理与人情暗自动容。大久保彦左卫门对太助十分倾慕，二人最终以父兄之礼结为师徒，还共饮了结义酒。 此时，相模屋和主管财政的官员勘定奉行川胜相互勾结，妄图掌控鱼市场的实权。这导致鱼价飞涨，百姓只能买到腐烂的沙丁鱼。愤怒的彦左卫门带着太助闯入川胜一派的酒宴，强行将腐烂的沙丁鱼卖给他们。然而，将军家光一句 “不得干涉政务” 的警告，让彦左卫门瞬间没了斗志。 太助得知川胜与相模屋的恶行后，觉得此事关乎天下大义，多次劝说彦左卫门上报朝廷，但彦左卫门一直犹豫不决，两人为此发生了争执。彦左卫门还下令禁止太助出入，太助只能整日借酒消愁。彦左卫门也迅速衰老，卧病在床。 太助接到急报后赶到彦左卫门身边，两人解开了心结，可彦左卫门还是离开了人世。太助和伙伴们下定决心重建鱼...

Fishmonger Tasuke and Shogun Iemitsu swap their identities in pretence for the protection of Iemitsu.

The supply of sea bream to the fish market has decreased, and the price has increased to a whopping 1 ryo, and unable to face his customers openly anymore, Tasuke closes the shop and goes on a trip to celebrate the first wedding anniversary with his wife Onaka. Staying at the inn, Tasuke sees that dishes from magnificent sea bream are served here, which is very cheap. Tasuke goes to a fishing village and finds out here that a rich merchant is stopping the shipment of fish...

In the third entry into this mega-hit series, Isshin Tasuke, a spirited fishmonger in Edo who looks just like Shogun Iemitsu undergoes a series of unforeseen troubles in his newly wedded life.

《一心太助》是1971年10月3日至1972年3月26日在富士电视台联播网播出的时代剧，由富士电视台与国际放映联合制作，全25集。播出时间为每周日20:00 - 20:56（日本标准时间）。 该剧以生性豪爽的江户鱼贩一心太助为主角，展现他运用智慧和胆识与恶势力正面对抗的风采，以及围绕他发生的江户町人温情故事，是一部明快幽默又不失严肃的单集完结型剧作。 此剧采用聚焦町人生活的暖心人情喜剧路线，细腻刻画了太助与妻子阿仲的深厚夫妻情、与担任同心的义兄之间的友情等家庭剧元素，播出期间广受好评。BS11频道曾在经典剧场时段重播该剧，2017年2月起BSTBS频道也在平日傍晚18点时段进行重播。

暂无剧情简介

Due to his uncanny resemblance to Shogun Iemitsu an Edo fishmonger finds himself embroiled in a power struggle between opposing factions in the Shogun's Ruling Council.