Tamakoma Second

"From now on, you are a team. With this team, you'll be promoted to Class-A, and then, will aim to be recruited to the Expeditionary Force."

- Takumi Rindō

Mikumo Unit, more commonly known as Tamakoma Second, is the B-rank #2 unit in Border. It is led by Osamu Mikumo.

Introduction Arc
Osamu, Yuma and Chika were invited to Tamakoma branch by Yuichi Jin, after asking Yuma to join Border from orders given by Takumi Rindo to retrieve Kuga's Black Trigger. Once at the headquarters, they meet Yotaro Rindo and Shiori Usami who explain Border's regulations, more details about its ranking system as well as more details about Tamakoma. Yuma and Osamu are then called to meet with Rindo. After hearing that Soichi Mogami, the person that Yuma was trying to meet had died, Rindo asks Yuma to join border to which Yuma denies.

Moments later, Replica explains Yuma's reasons to coming to earth: meeting with Mogami Souchi in an attempt to revive his father. He then tells Osamu about Yuma nearly dying and his father sacrificing his life to save him at the last minute. Yuma tells Jin that he plans to head back to his home because living on earth as a neighbor would just give him trouble. Replica then tasks Yuma with giving him a new will to live and to join Border as an agent.

Before fulfilling the task, Osamu is pulled away by Shiori to hear that Chika wanted to join Border in hopes of finding her brother Rinji and her friend Aoba. Though indecisive at first about her decision, the two accept her decision as Osamu then heads up to Osamu. During the conversation, Osamu asks Yuma to join in hopes to help bring back Chika's comrades then asks for his assistance. The two talk about Osamu's selflessness, then Yuma soon agrees to help Osamu and Chika, under the condition that Osamu would be the captain of their squad. To Osamu's shock and exclaiming how he is far more inferior to Yuma, He simply explains that Osamu being captain is the way that it should be. After hearing the good news, Rindo assigns Osamu, Yuma and Chika to being a squad.

B-Rank Rank Battles Arc

 * Tamakoma Second vs. Yoshizato Unit vs. Mamiya Unit: Win
 * Tamakoma Second vs. Suwa Unit vs. Arafune Unit: Win
 * Tamakoma Second vs. Suzunari First vs. Nasu Unit: Win
 * Tamakoma Second vs. Ninomiya Unit vs. Kageura Unit vs. Azuma Unit: Loss (Ninomiya Unit's victory)
 * Tamakoma Second vs. Katori Unit vs. Kakizaki Unit: Win
 * Tamakoma Second vs. Ōji Unit vs. Ikoma Unit: Win
 * Tamakoma Second vs. Kageura Unit vs. Azuma Unit vs. Suzunari First: Win

Trivia

 * Excluding Usami, all the original members' surnames have something to do with the sky. Kumo from Mikumo means "cloud", ku from Kuga can mean "sky" or be combined with 気 to mean "air", and ama from Amatori means "rain".