TV-Series
Description
Reinforce Zwei manifested in early spring 0067 as a Unison Device born from Hayate Yagami's split Linker Core, fused with remnants of the original Reinforce Eins' core. This act forged her as Eins' spiritual successor, inheriting both the name "Reinforce" and the title "Blessed Wind." Commonly called "Rein," she later adopted the surname Yagami in continuities like EXCEEDS and Gun Blaze Vengeance, signifying her place within the Yagami family.

Her default physical form stands approximately 30 centimeters tall, notably smaller than most characters save Agito. While capable of shapeshifting to adolescent human size, this transformation demands substantial mana, making it impractical for combat. Turquoise eyes and hair define her standard appearance. She wears protective Knight Clothing based on the inner design of Hayate's Knight Armor, prioritizing agility over defense. This outfit exhibits minor design variations across continuities, such as differences in undersuit zippers and waist cloaks in the Reflection movie timeline.

Functionally classified as a Unison Device or "control device," she specializes in auxiliary magic management, synchronizing with Hayate with minimal reaction delays of 2 milliseconds. She can also Unison with Wolkenritter members Signum and Vita to enhance their combat capabilities, though less efficiently than with Hayate. During Unison, the hosts' eyes temporarily take on her turquoise coloration. Offensively, she wields the Device Book of the Azure Sky and employs ice-based spells like Frigid Dagger and Frierenfesseln, holding a synthetic mage rank of A+ with white magic coloration.

Her professional path began after passing the Time-Space Administration Bureau's employment examination in autumn 0069, leading Hayate to entrust her with the Book of the Azure Sky. By April 0071, she actively supported Hayate in Relic-related missions, including capturing Gadget Drones. Within Riot Force 6 during StrikerS, she served as an Air Sergeant Leader and Chief of Staff, operating from the Long Arch headquarters and gaining renown as one of the Bureau's most popular examiners. Later, in ViVid, she contributed to creating the Hybrid-Intelligent Device Asteion for Einhart Stratos. During Force events, she assumed human-sized form to serve as Vice-Commander of the TSAB Marine Defense Force under Hayate, coordinating operations for Special Duty Section 6. Her role expanded to mentoring Lily-Strosek, leveraging similarities between Unison Devices and Strosek-series Reactors, including joint mock battles.

Her core relationships revolve around the Yagami household, where she is treated as family. She shares a mentorship dynamic with Lily-Strosek and a notable rivalry-turned-sibling bond with the Unison Device Agito, also adopted by the family. This rivalry, initially fueled by Agito's fire affinity opposing her ice-based spells, resolved through their coexistence within the family structure.

Alternate continuities present variations: the movie timeline adjusts her birth year to 0066 in Reflection, while Brave Duel reimagines her as Eins' younger sister within the Yagami family. Portable game scenarios depict contexts where the original Reinforce Eins survives, potentially altering Zwei's developmental circumstances, though her core functions remain consistent.