Tadashi Kikuchi serves as secretary to Ainosuke Shindo, a relationship rooted in their childhood. As the son of the Shindo family's gardener, Tadashi's family served the household for generations, establishing his subordinate position early. He first encountered a young Ainosuke crying by the family pool and offered him a skateboard, becoming the person who taught Ainosuke to skate. This shared activity became Ainosuke's primary escape from his strict upbringing, though Tadashi later expressed regret for introducing it due to the severe consequences. Tadashi displays unwavering loyalty, consistently performing duties without voicing personal opinions. This trait solidified after an incident where Ainosuke's father, Aiichiro Shindo, burned Ainosuke's skateboard. When Aiichiro demanded Tadashi's compliance, Tadashi responded with "I have no opinions," a behavioral pattern continuing into adulthood. As an adult, Tadashi manages Ainosuke's political affairs and secretly oversees operations at "S," an underground skateboarding race. His responsibilities include coordinating capmen, monitoring security feeds, and occasionally piloting helicopters during events. Physically, Tadashi stands 182 cm tall with a slender build, purplish-black hair, green eyes, and a distinctive mole under his right eye. Character designers gave him smaller eye highlights to convey a "dark and hopeless" demeanor, with director Hiroko Utsumi describing the approach as creating "dead eyes" reflecting his emotional suppression. His attire consists of subdued formal suits, though his tie color—often pink or lavender—subtly references his connection to Ainosuke. At "S," Tadashi adopts the alias "Snake," wearing a green bomber jacket, red cap, and black sweatpants. His skating style features fluid, dance-like movements that directly influenced Ainosuke's technique. Despite limited recognition at "S," Tadashi demonstrates exceptional skill, easily outperforming skaters like Miya Chinen during qualifiers. His regular stance (left foot forward) and snake-themed skateboard design align with his alias. Tadashi's pivotal development occurs when he enters the "S" tournament as Snake to challenge Ainosuke directly. He aims to force Ainosuke to renounce skateboarding if victorious, believing this would protect him from political ruin caused by "S"-related incidents. This confrontation reveals Tadashi's internal conflict: deep concern for Ainosuke's well-being clashing with his submissive role. After losing to Langa and witnessing Langa reignite Ainosuke's joy in skating, Tadashi forfeits his own match, recognizing skateboarding remains Ainosuke's essential emotional outlet. Following a political scandal involving Diet Member Takano, Ainosuke declares Tadashi will remain "his dog for life," a statement Tadashi accepts with a rare smile and blush, reinforcing their codependent dynamic described in production materials as "connected with unbreakable chains." Tadashi's birthday is November 22, his blood type is A, and he prefers oysters. He lacks hobbies. His daily schedule revolves entirely around Ainosuke's needs, often involving sleepless nights. A hypothetical dog form would be a black Shiba Inu, reflecting his loyal but understated presence. Symbolically, his surname "Kikuchi" contains the kanji for chrysanthemum (菊), matching the flower motif on Ainosuke's skateboard and his November birth flower.