A lordless samurai and his son who have left behind their home clan, were traveling when they got stopped by a young samurai. This young man is seeking revenge against the father and kills him. The 10 year old son Tsurunosuke (Tamayama Uta) almost gets killed too but a merchant intervenes. The merchant, Wasuke (Tsugawa Masahiko) an owner of an agar wholesale business, Ikawaya, offers to buy the samurai's revenge with one bag of ginnikan (Edo period's silver currency). The bargain is accepted, and Tsurunosuke, now a homeless orphan, has no choice but to go with Wasuke to become a lowly apprentice in his shop in Tenma, Osaka. The shop's head clerk, Zenjiro (Shiomi Sansei) is very strict with him and not at all pleased that the precious ginnikan was exchanged for this boy. That hard-earned money was intended for the rebuilding of Osaka's Tenmangu (shrine), which was destroyed in a fire. Of course, the boy is unhappy with his situation, too. He also dislikes the shop's main source of livelihood: agar. To top it off, he is sent to learn to make agar in a production site in Fushimi, Kyoto... Three years have passed, the boy, now 13 year old, comes back to Ikawaya. Taller and a bit more docile than before, he takes on the apprentice name, "Matsukichi". Matsukichi (Hayashi Kento) starts his new life as a humble apprentice. But inside of him, the proud Samurai spirit still lingers...