Mitsuru Tsutsui is a supporting character in the anime 3D Kanojo Real Girl, appearing primarily in the second season. He is the father of the protagonist Hikari Tsutsui and his younger brother Kaoru Tsutsui, and the husband of Kie Tsutsui. By profession, Mitsuru works as a researcher specializing in adhesives, a detail that reflects his analytical and methodical nature. In terms of personality, he is described as an introverted individual who is generally good-natured but quite passive, often accepting or allowing events to happen without active resistance. Despite this passivity, he is portrayed as a devoted husband and a father who truly cares for the well-being of his family. His motivations center on providing for his household and maintaining family harmony, though his actions sometimes fall short of that ideal. A significant development in Mitsuru’s story occurs when it is revealed that he had been seeing another woman named Kono. This extramarital relationship causes Kie to file for divorce, and she subsequently decides to take one of their sons, either Hikari or Kaoru, back to her hometown. This event creates a major rift in the Tsutsui family and forces Mitsuru to confront the consequences of his choices. His role in the story is that of a supporting father figure whose personal failings introduce a serious conflict that affects the protagonist’s home life. His key relationships include his wife Kie, whose trust he betrays; his sons Hikari and Kaoru, whose stability he jeopardizes; and Kono, the woman involved in the affair. Over the course of the narrative, Mitsuru’s character is defined more by the aftermath of his actions than by active growth, as he struggles with the breakdown of his marriage. His notable abilities are limited to his professional expertise in adhesives research, which underscores his identity as a career-focused individual. Overall, Mitsuru Tsutsui serves as a realistic example of a flawed parent whose private decisions have lasting repercussions on those closest to him.