"Peacemaker Kurogane: Friend" is a historical action anime set in the late Edo period of Japan, focusing on the Shinsengumi, a special police force in Kyoto. The story centers on Tetsunosuke Ichimura, a young boy who joins the Shinsengumi to avenge his parents' murder by a Choshu rebel. Tetsunosuke's older brother, Tatsunosuke, initially opposes his decision but eventually supports him, joining the Shinsengumi as well. The series explores Tetsunosuke's journey as he trains to become a skilled swordsman and grapples with the harsh realities of war, loyalty, and vengeance.

The narrative delves into the internal dynamics of the Shinsengumi, highlighting key historical figures such as Commander Isami Kondo, Vice Commander Toshizo Hijikata, and swordsman Soji Okita. These characters are portrayed with a mix of historical accuracy and fictional embellishment, showcasing their leadership, camaraderie, and conflicts within the group. Tetsunosuke's interactions with these figures shape his growth, as he learns the importance of discipline, sacrifice, and the complexities of justice.

The plot intertwines historical events with personal struggles, depicting the Shinsengumi's efforts to maintain order in Kyoto amidst political turmoil and rising tensions between factions. Tetsunosuke's quest for revenge becomes increasingly complicated as he forms bonds with his comrades and begins to question the morality of his actions. The series balances intense sword-fighting sequences with moments of introspection, exploring themes of honor, duty, and the human cost of violence.

"Peacemaker Kurogane: Friend" also introduces fictional elements, such as Tetsunosuke's encounters with supernatural forces, which add a layer of mysticism to the historical setting. These elements serve to heighten the stakes and deepen the protagonist's internal conflict. The anime concludes with Tetsunosuke's continued evolution as a warrior and his acceptance of the responsibilities that come with his chosen path, leaving room for further exploration of his character and the Shinsengumi's legacy.