Mikoto Saito is a character from Cardfight!! Vanguard Divinez. She is a second-year high school student who attends the same school as Akina Myoudou. She leads a double life as a talented singer and a popular idol, while also being a top-tier player in the online Vanguard community under the username UsaBerry. Despite her polished public image, she has a clumsy and talkative personality and originally started playing Vanguard anonymously online to build her confidence.

Mikoto is the owner of the Fated One of Ever-changing, Krysrain, a card from the Lyrical Monasterio nation. In battle, her deck relies on fielding a variety of different unit cards to power up Krysrain and unlock its full abilities, including drawing cards, energy charging, and boosting attack power or critical. Her playstyle emphasizes versatility and adaptability, reflecting her need to balance her idol career, school life, and cardfighting.

Her motivation in the story is shaped by her participation in the Fated Clash. She is chosen as one of the Fated Ones and uses her analytical skills and online experience to understand opponents and strategize. She quickly befriends Akina and the other Fated Ones, becoming a key ally. She is a member of the Mythisch Fighters in later arcs, including the Parallactic Clash, where she provides tactical oversight and works to protect both her world and the mysterious realm of Fantasma.

Mikoto develops over the course of the series from someone who mainly played Vanguard online to a confident physical player who embraces the challenges of the Fated Clash. She upgrades her deck as the story progresses, gaining new aces such as Krysrain Cadenza and the Mythisch of Ever-changing, Urtineas. Her relationships with Akina and the other fighters deepen as she learns to trust her instincts alongside her data-driven approach. She remains a warm and supportive presence within the group, often helping to keep morale high while maintaining a professional edge in competition.