From references made by Kotomi, it seems that the Aliens arrived on Earth either shortly before her birth or at some point during her early childhood; when she was in college, there was still some excitement surrounding their arrival and she took at least one college course that revolved around an optimistic line of thought that included business activities with worlds beyond our solar system. Like everyone else, though, educators, businesspeople, and Kotomi herself soon recognized that the presence of Aliens on Earth was not going to change life as it had existed in any major way, so they soon moved onto other things. Kotomi barely had a conscious memory of having studied topics relating to the brave new frontiers that she and others had dreamed about when she was young, only being reminded of it when she finds a copy of a book on the subject that she read while a student after she, Mayuko and NieA clean out a storage room on the bathhouse’s second floor.

Kotomi has all the traits and skills one expects to see in a successful professional. She is self-assured, shows keen leadership abilities, is highly organized, and is very pragmatic and levelheaded in her approach to life. Her competitiveness is so fierce that when she is faced with a challenger she disregards all other concerns but instead throws every resource she can muster at the “threat,” even if it means not achieving whatever goal she may have been striving toward when the challenger first presented him- or herself. For example, when young Chie Karuta makes a disparaging comment about the promised prizes for the Enohana Bathhouse’s video game tournament, Kotomi abandons all thought of promotions and instead commands her staff to defeat all comers.

Kotomi displays gentler emotions, too—mainly a fondness for the bathhouse and those who live and work there. She tells Mayuko at one point that she used to visit it while in school and that she couldn’t bear the thought of the place being closed down, so she bought it. She also treats the staff with unfailing fairness and kindness despite her general nature. She permits Mayuko to live above the bathhouse, rent free, except for a few hours of labor every day after the baths have closed; tolerates the continuing antics of the only-occasionally productive (or even useful) NieA, but still draws lines when NieA’s demands get too outrageous or presumptuous; overlooks the disturbing pyromaniacal tendencies of the bathhouse’s boiler operator and handyman, Mr. Yoshioka, but at the same time remains seemingly oblivious to the fact he has a crush on her; and remains supportive of the aged bathhouse matron Enoshima, who is so frail she can perform little work but tend the flowers around the building and greet customers. Kotomi serves as more than just a landlord or boss to the people who live and work at the bathhouse--she also serves as something of a mother. Her relationship with Mayuko is particularly close to that of a mother with a daughter, often imparting sage advice to the younger woman, the best of which is the statement that the only person who can provide direction to Mayuko’s life is Mayuko herself. Despite the occasional slip into outrageousness—such as when she loses her cool during the video game tournament—Kotomi is an excellent role model for the isolated, insecure Mayuko.

As the series progresses, Kotomi’s emotional and pragmatic sides collide as the financial drain of the ailing Enohana Bathhouse reaches a critical point. Although the bathhouse is the one place that Kotomi feels content and as if everything is all right with the world, Kotomi eventually has to face the fact that she must let the place go if it doesn’t become profitable. She spends many long nights going over ledger sheets, drinking progressively more and growing more depressed. She does not, however, lash out at those around her, nor does she fall victim to indecisiveness but instead, when it seems that she is out of options, she shakes off the depression and acts: She starts taking steps to sell the bathhouse, but she makes sure the people who have come to depend on her are aware of the troubled times that are almost certainly upon them, showing again that she is more of a kind mother figure to the staff than just a boss and property owner. Her behavior is also a further example to Mayuko who cruelly mistreated NieA despite the fact that many of Mayuko’s problems were coming from her own insecurities rather than any outside forces.

In the end, Kotomi’s belief in her own abilities help to turn the economics of the bathhouse toward the positive, and she cancels its sale at the eleventh hour.