Yamato Mikoto hails from the Far East, orphaned several years after birth. Tsukuyomi and Takemikazuchi took her into their orphanage, where she resided for years before joining the Takemikazuchi Familia. During this time, she and other Familia members frequently spirited Sanjouno Haruhime out of her mansion for nighttime play, straining relations between Haruhime's father and the shrine, though they persisted regardless.

Mikoto possesses long black hair tied in a ponytail, bluish-purple eyes, and stands 1.57 meters tall. Her attire typically features a purple kimono with a sarashi underneath, a dark red sash, thigh-length boots, a red shoulder guard on her non-weapon arm, and arm guards. She secures her katana within her waist sash.

Her personality is serious and honorable, rejecting cowardly tactics even in emergencies, such as disapproving of using "Pass Parade" to evade monsters. Fiercely loyal to her friends, she cares deeply for their well-being. Mikoto is humble, often downplaying her abilities or contributions and becoming embarrassed when acknowledged. She struggles to lie effectively. She cherishes relaxing in cypress baths or hot springs, revealing a softer side.

Approximately two years prior to the main events, Mikoto and the Takemikazuchi Familia relocated to Orario to fund their shrine. She attained Level 2 shortly before encountering Bell Cranel. She later temporarily converted to the Hestia Familia to aid them in the War Game against the Apollo Familia, planning to return to her original Familia within a year.

As a Level 2 adventurer, Mikoto wields enhanced physical abilities and senses surpassing Level 1. Trained by Takemikazuchi, she is a skilled martial artist proficient in judo and multiple weapons: katanas, spears, axes, bows, short swords, shuriken, and kunai. Her signature techniques include "Mikazuchi," a powerful aerial throw, and "Zekka," an advanced quick-draw capable of injuring high-level monsters like the Level 5 Amphisbaena. Though she knows ninjutsu, she avoids it due to its reliance on deception, but will use it to protect loved ones.

Her gravity-based magic, "Futsunomitama," creates a dome-shaped force field to trap targets. She can cast it while moving via the high-level technique "Concurrent Chanting." Her skills include "Yatanokurogarasu," detecting previously encountered monsters within range, and "Yatanoshirogarasu," locating Familia members. She also possesses the Development Ability "Abnormal Resistance" to negate poison and similar effects.

Mikoto wields several weapons: "Kotetsu," a katana forged by Welf; "Chizan," a black short sword gifted by Takemikazuchi; "Shunsan," a superior katana; and "Shakuya," kunai made from Blood Onyx.

Her relationships are defined by loyalty, viewing Takemikazuchi as a father figure. Within the Hestia Familia, she forms close bonds with Bell Cranel, Welf Crozzo, and Liliruca Arde, maintaining her commitment to the Takemikazuchi Familia despite her temporary transfer.

Mikoto is a skilled cook, having honed her abilities using limited supplies at the orphanage. Her dishes earn praise even from the goddess Hestia.

Her development involves learning to reconcile honorable principles with pragmatic tactics when necessary, such as employing ninjutsu in critical situations to protect allies. Her combat skills evolve through experiences like expeditions and the War Game, where her contributions prove vital to the Hestia Familia's successes.