Futayo Honda, only daughter of Tadakatsu Honda (one of Matsudaira's Four Heavenly Kings) and Kazuno, was born in Mikawa. Her parents subjected her to intense martial training from childhood, specializing in spear combat. This forged exceptional fighting prowess but left her largely ignorant of social norms and the outside world. She attended middle school with her second cousin, Masazumi Honda, before political upheavals in Mikawa separated them.

Preceding the main events, Futayo was appointed commander of the Mikawa Security Corps, the Far East's sole armed group recognized by the Testament Union. Her duties included escorting the aerial city-ship Musashi to Aki Province. Her father Tadakatsu expressed his wish for her to choose her own future: joining Musashi Ariadust Academy or inheriting the Honda name.

During the Mikawa Meltdown on April 20, 1648, she accompanied Tadakatsu Sakai and Yasumasa Sakakibara to welcome President Tadatsugu Sakai. Under her father's orders, she attacked Sakai to demonstrate her skill, though he effortlessly parried her. Later, while securing Musashi's route outside Mikawa, she witnessed Shin-Nagoya Castle's destruction. Faced with aiding her parents under Tres España's attack or continuing her mission, she recalled her father's desire for her independence. She prioritized duty, ordering the Mikawa Corps to align with the Testament Union.

The next day, encountering Tres España's forces, her attempt to reclaim her father's weapon, Tonbokiri, resulted in Far Eastern embarrassment due to Muneshige Tachibana's intervention. She subsequently arrived on Musashi and agreed to support Masazumi in a Class 3-Plum political dispute. During a three-duel match, she faced Kimi Aoi. Despite Futayo's confidence and high-speed attacks, Kimi exploited her predictability and emotional vulnerabilities, securing victory. Kimi's rebuke prompted Futayo to pledge loyalty to Horizon Ariadust, accept defeat, and join Musashi's campaign. She was later appointed Vice Chancellor of Musashi Ariadust Academy.

In subsequent battles, positioned defensively near Musashi, she fought Muneshige Tachibana using Tonbokiri's abilities. Muneshige outmaneuvered her, leveraging experience from battling her father. As Muneshige prepared to fire on Musashi, threatening the Far East's sovereignty, Futayo recalled a sparring session with Tadakatsu. Reacting with a surge of rage, she caused Muneshige to halt his attack.

Futayo possesses dark blue hair tied in a high ponytail with a winged accessory, purple eyes, and features prominent breasts, thick thighs, and a slender waist. She typically wears a modified Musashi Ariadust Academy uniform with blue accents and blue armor plates at her arms, shins, and waist. A red katana is often sheathed at her waist, though she primarily wields Tonbokiri in combat.

Her personality blends polite, respectful speech with fierce pride in her family. Exceptionally skilled in combat, she is easily embarrassed and socially awkward, sometimes misinterpreting fundamentals like sex due to isolation. A strong sense of duty, instilled by training, gradually gives way to independent choices.

She inherited the Divine Weapon Tonbokiri after her father's death. This telescopic spear holds two key abilities. Its Normal Drive slices tangible and intangible targets within 30 meters by reflecting the target's image upon its blade and releasing a beam upon the command "Bind, Tonbokiri!" Effects are permanent, severing names or abilities. Its Super Drive, demonstrated only by Tadakatsu, extends this to cutting concepts like distance. Futayo also utilizes the "Soaring Wings" ability, granting combat acceleration but causing momentary vulnerability if interrupted.