Tetsuya Kusakabe (日下部哲也, Kusakabe Tetsuya) is the second-in-command of the Namimori Middle Disciplinary Committee and, in the future, the second-in-command of the Foundation; as such, Kusakabe is extremely loyal to Hibari. In the future, he has travelled around the world with Hibari researching the Rings and Boxes.
Kusakabe is first seen in the lobby of the hospital, conversing with another prefect on the whereabouts of Hibari after Ryohei Sasagawa is attacked; however, it is revealed that as soon as he left the hospital, he was brutally beaten.
Kyoko Search & Gamma Battle
Kusakabe appears at the end of this plot point along with Hibari, as they were both traveling the globe to search for the origins of the Boxes. He affirmed that Yamamoto and Gokudera were going to survive the heavy injuries the two suffered as a result of their battle with Gamma. He assists in carrying the fallen Vongola back to the hideout through Hibari's personal base, which is connected to the Vongola Base, even offering to carry them both.
He does, however, assist in the debriefing. He takes Hibari's place, as he hates crowds. He begins by explaining that Kurokawa asked them to send Hibird out to search for Kyoko. He goes on to reveal that, Hibird included, the Vongola have over 10 different methods of backup communication, but the reason the SOS on the Hibird disappeared at the shrine was because of a faulty battery.Tsuna is surprised to hear Kusakabe reveal that he and Hibari are still affiliated with their childhood Disciplinary Committee. But, when Fuuta brings up the topic of their search for Box Weapon information, Kusakabe directs them to refer to Hibari for any more about that, as he intended on hanging around for a while.
Melone Base Invasion
Kusakabe brings reinforcements to the base after Gokudera, Yamamoto, and Ryohei have all already fought. Kusakabe is leading the backup team of himself, I-Pin, Lambo, and Chrome their objective being to prevent Gokudera and Ryohei from being captured by the enemy. During Hibari's fight with Genkishi when Hibari's Box Weapon loses control, he saves the lives of Gokudera, Yamamoto, Ryohei and Lal by carrying them all on his back, due to them being too injured to walk.
His reinforcements are later seen captured by the enemy along with the rest of Tsuna's Family.
He was seen watching Tsuna's battle with Byakuran. Later, after Tsuna had defeated Byakuran and both he and the people from the past were about to leave, he was seen in the Vongola hideout dojo biding Hibari farewell, to no response.
Kusakabe is seen piloting a helicopter, dropping Hibari off on Simon Island wishing him luck in his fight against Adelheid.
- His strength was later shown in the Melone Base Invasion when Kusakabe was able to lift Future Lal Mirch, Yamamoto, Gokudera, Chrome, and Future Ryohei on his back and still run at a considerable speed away from Hibari's out-of-control Box Weapon.
- According to his segment in the Haru Haru's Interview: Dangerous, it takes him three hours to style his hair.
- He has the same voice actor as Uno and Bono.
- Future Hibari calls him "Tetsu."
- Romario and Kusakabe seem to share a friendship; this is probably because Dino and Hibari constantly train with each other.
- He seems to be great at handling kids. This is proven by the fact that Lambo and I-Pin enjoy playing with him when they were sent to the future.
- He was featured in Yakusoku no Basho e - vs. Millefiore.