Hayakawa Yui (Yuna Kuroshima) is 16 years old. She is only good at running, but she somehow manages to lead a cheerful high school life. However, one night under a full moon, she is sent back to the Warring States Period in a time machine built by her younger brother Takeru (Shota Shimoda), who loves to invent things.

Yui (Yuna Kuroshima) was supposed to be a modern high school girl, but time slips brought her to the Warring States period. She spends her days as Yui Yunosuke. While she is disappointed not to meet the young lord Tadakiyo (Kentaro), she hears about a “kakekurabe tournament” in which retainers of the Amano family compete against each other. Tadashi, hoping to become a retainer of the Amano family, makes a direct appeal to Nobumo (Issei Ogata), a retired official, by showing that he is as...

When Yui (Yuna Kuroshima) returns to the present day from the Warring States period and learns that her young lord Tadakiyo (Kentaro) is destined to die in a battle soon, she is determined to go back in time and save him. Her younger brother Takeru (Shota Shota), overcome by her enthusiasm, invents a new good for Tadashi, the “secret sword, Dendenmaru,” and makes him carry it.

Yui (Yuna Kuroshima) experiences the battle firsthand and is greatly shocked. On the evening of the victory party, she meets Ayame (Yusaku Mori), an onnagata (female actress) in a theatrical troupe. That night, he is astonished to hear that Fukie (Shizuka Nakamura) of Kanegae, the daughter of a local wealthy samurai, is to spend the night serving under the young lord Tadakiyo (Kentaro).

Yui (Yuna Kuroshima) returns to the present day to save the Hagi Army led by the young lord Tadakiyo (Kentaro) from a pinch. She asked her younger brother Takeru (Shota Shota) to take the goods “Mabobyo-kun” to the warring states. As a foot soldier named “Tadinosuke,” Yui follows Tadakiyo's horse through the battlefields and struggles mightily. Tadasuke's success was rewarded by Nobumo Amano (Issey Ogata), who made arrangements for him to become Tadakiyo's “stable keeper”.

The members of the Hayakawa family are surprised to see the dying young lord Tadakiyo (Kentaro) sent back from the Warring States period in a time machine, but he survives thanks to the efforts of his mother Mikako (Hiroko Nakajima). Yui (Yuna Kuroshima), who is still in the Warring States period, is comfortably expecting Tadakiyo to return in three minutes because of the time machine's mechanism.

The young lord Tadakiyo (Kentaro), who was sent to the present day in a time machine to receive treatment for his injuries, developed a high fever and was unable to return to the Warring States. Yui (Yuna Kuroshima), on the other hand, continues to wait for a chance to return a month later, but she is pursued on suspicion of involvement in the wakamikun's disappearance.

For saving the young lord Tadakiyo (Kentaro) from a tight spot, Yui (Yuna Kuroshima) is appointed as the young lord's bodyguard and is sent to train as a warrior in the Amano family. Meanwhile, Tadakiyo meets her fiancé, Matsumaru Akoh (Rina Kawase). In addition to Princess Akoh, Fuki (Nakamura Shizuka) is also waiting in the wings, which makes Tadaki feel uneasy.

Yui (Yuna Kuroshima) returns to the present day, but she is severely depressed to learn that the time machine has run out of fuel and she cannot return to the Warring States period. Her younger brother Takeru (Shota) is moved by her enthusiasm, and buys enough fuel for one more round trip.

Yui (Yuna Kuroshima) is trapped in Takayama as a substitute for Akoh (Rina Kawase). Hearing this, the young lord Tadakiyo (Kentaro) desperately searches for her. Tadakiyo finally crosses swords with Naruyuki (Matsushita Yuya), who seems to know what he is up to. Takayama then offers to marry Yui to Sokuma (Ryo Kato), the heir to the family.