Mitsuki Sanada is a main character in the anime Dual! Parallel Trouble Adventure. She is a seventeen-year-old high school student who is widely regarded as the most popular girl at her school, with many male admirers who constantly send her gifts and cards. Despite this attention, she is not particularly interested in any of them. She lives alone with her father, Dr. Ken Sanada, a scientist who conducts experimental research on parallel worlds in his basement. Mitsuki is intelligent, capable of managing schoolwork, housework, and later mecha piloting, and she is described as beautiful with long brown hair and brown eyes.

Mitsuki’s initial role in the story is to lure Kazuki Yotsuga to her father’s house under the pretense of liking his stories about giant robots. This is a ruse; her father wants to study Kazuki because he is the only person who can see a parallel world where giant robots battle. During an experiment, Mitsuki accidentally activates her father’s quantum portal device, sending Kazuki into the parallel world. She follows him shortly after and arrives in that world a month before he does. Stranded in an alternate reality where a war is being fought between the Earth Defense Force (EDF) and the Rara Army, she volunteers to become a robot pilot, hoping that by helping to end the conflict, the parallel world’s Dr. Sanada will have time to develop a way to send her and Kazuki back home. She pilots the red Core Robot Number Two and proves to be an exceptional mecha pilot.

Personality-wise, Mitsuki is hotheaded, short-tempered, and somewhat spoiled, often acting in a way that suggests she enjoys being the center of attention. She can be immature, especially in how she handles her feelings for Kazuki: she is clearly attracted to him but covers it up by treating him abrasively, teasing him and annoying him constantly. This tsundere behavior masks a genuine affection that becomes more evident as the series progresses. She is also easily manipulated, a flaw that the Rara Army exploits when they capture her toward the end of the series and coerce her into piloting the complete version of the Himiko mecha. When Kazuki is lost behind enemy lines, Mitsuki is the one most deeply affected.

Mitsuki’s key relationships include her bond with Kazuki, which develops from a reluctant partnership into a strong romantic attachment that she struggles to express directly. She also has a complicated dynamic with her own father, Dr. Ken Sanada, who in the original world is a well-meaning but eccentric scientist, while in the parallel world he is the leader of the EDF. Additionally, she interacts with her counterpart from the other world, Mitsuki Rara, who eventually defects from the Rara Army and comes to live with Kazuki and the others.

Over the course of the series, Mitsuki grows from a somewhat shallow, popularity-driven teenager into a responsible and dedicated pilot who willingly fights for the safety of both worlds. Her capture and subsequent rescue deepen her emotional maturity, and she becomes more open about her feelings for Kazuki, though she never fully abandons her teasing exterior. At the conclusion, when the two parallel worlds merge into one as a result of another accidental action by Mitsuki, her relationship with Kazuki remains unchanged, implying that her feelings endure the altered reality. Her notable abilities include exceptional skill as a mecha pilot, particularly with the Core Robot Number Two, as well as domestic talents such as cooking and housekeeping.