Saki Kasukabe (春日部 咲 Kasukabe Saki) is a student at Shiou University and the only non-otaku main character. She is the childhood friend/girlfriend of Makoto Kousaka who initially hates otaku and their lifestyle, but she is forced to hang around the Genshiken in order to be with Makoto. Later on, she is compelled to become a member herself.
As the series progresses, Saki's general attitude and behavior towards Genshiken and its members evolve from barely tolerating them to holding them as dear and valuable friends. She slowly stops abusing Genshiken members (but will still continue teasing them) and even takes part in their activities, though much to her chagrin.
In spite of swearing to destroy Genshiken, she goes out of her way to save the club - multiple times, in fact at her own expense.
In Genshiken Nidaime, she has since graduated and is working as an entrepreneur for her fashion line. Outside of a few chapters centered on her, she mostly appears as a supporting character.
Saki is an attractive and fashionable young woman in her early twenties with mid-back length hair (it is implied to be dyed light brown) that is split on either sides and brown eyes.
She is usually seen with a cigarette in hand, but after a certain incident in the series, she has since quit smoking. Because of her figure (and quite possibly because she's the only other female at the time), Kanako Ohno is always pressuring her to cosplay, much to her annoyance.
Saki is an assertive, down to earth, practical and at times manipulative individual who can be easily angered and quite ruthless when the moment calls for it. She spends most of her time physically abusing and teasing the male members of Genshiken, and notably develops an antagonistic friendship with Harunobu Madarame. She barely tolerates the circle of otakus only due to Makoto Kousaka , who ironically is one of the most hardcore otaku of the series, and gets infuriated when people call her one.
Early on, she wants nothing more than to destroy Genshiken to free her boyfriend. In fact, she almost quite literally succeeds in doing so, but saves the group and even returns favors to them out of guilt. In a twist of irony, she has come to the club's aid during times when it is threatened by outside forces.
In contrast to being a hothead, Saki can break down and cry quite easily, especially if she feels ridden with guilt. Although she tends to cause mischief in the club room, she doesn't do it out of malice and will apologize once she hurts anyone's feelings.
Towards the end, Saki has shown she cares for the club and its members as she is emotional at the thought of graduating and leaving it behind.
Plot (SPOILER ALERT)
After turning down cat calls from other guys, Saki noticed a rather pretty looking boy walking by wearing his headsets. As she tries to strike up a conversation with him, the boy instantly recognizes her as an old childhood friend. Saki is shocked to find out the boy is none other than Makoto Kousaka from grade school, whom she used to tease for his shaved head. When she asked what Kousaka was listening to, he responded that he was listening to a song from his favorite seiyuu (voice actress), which confused Saki.
Upon entering Genshiken, she is disgusted by the club members and their hobbies and fetishes. She is also taken aback at how much of an otaku Kousaka is. She constantly berates everyone in the club and vows to destroy it someday. Not long after, Kanako Ohno joins Genshiken and, being the only other female, immediately becomes close to Saki. However, despite confiding within each other on more feminine matters, Saki is far from sharing the same passion for cosplay as Ohno.
Once Saki heard about Genshiken being among the clubs being forced to dissolve via inactivity, Saki was grinning ear to ear. However, after seeing the club being humiliated by an encroaching Haraguchi, Saki's mood went from ecstatic to indignant. Disappointed by Genshiken's lack of resistance and worried that Kousaka may be forced to join the Manga Club under Haraguchi, Saki ironically sets out to save the club. Utilizing inside information gained by the First President, Saki manages to compel the Club Council Vice Chairman Kitagawa to reverse their decision.
Now that the club is saved due to her efforts, the First President asks Saki if she's willing to join, to which she immediately declines. In any case, the First President considers her a member anyways, seeing as how much she "uses the place." His cryptic words immediately spark a reaction from Saki, who then questions him how he knew about the council vice chairman's dirty laundry as well as what Saki has been doing in the room while others were away. Saki then assumes the President has some kind of spy cameras hidden somewhere. He enigmatically responds, "If I were that kind of person, there would already be a large number of people, regardless of gender, who could no longer attend this school. But there are no such people, are there?" These words sow terror into Saki's heart, and she sheepishly joins Genshiken as a result. The President then tells her, "For now it would be best to not use the 1st or 2nd floor bathrooms... I'm just joking." His words obviously do not provide any more comfort to Saki.
While Genshiken was recruiting new members, Saki took it upon herself to haze the newcomers. Once her horror stories of the Genshiken room failed to do so, she utilized Kousaka's elite video game skills to break the newcomers' pride. So far, she has only dissuaded one, while the other eventually returns after not too long.
One day, while on the way to a Genshiken meeting from Kousaka's messy house, she slips on one of his magazines and hits her head on a table. During the meeting, she taps a bookshelf behind her, causing an item to fall and hit her head on the exact same spot. Frustrated with the clutter, she pushes everyone to clean up the Genshiken room and remove any unnecessary items. Once all the old collectibles were moved to a storage area outside, Saki lights a cigarette and imagines burning the items up. Her thoughts were suddenly interrupted by the appearance of Madarame, which startles her and makes her unintentionally drop her cigarette on the items. Everything immediately catches fire, and Madarame pulls Saki away from the flames, but they panic nonetheless. Saki grabs a bucket of water, but due to the bumps on her head and panicking from the fire, she is disoriented and accidentally splashes Ohno with it. Council Vice Chairman Kitagawa arrives and tells everyone to evacuate immediately.
Since the fire incident, The Genshiken are suspended from their club room pending an investigation, and had to hold meetings at each other's apartment rooms. The group is also forced to do community service in repentance for the fire, causing them to miss the next Comiket. When Madarame expresses his frustrations, Saki slowly begins to tear up and cry. Kousaka explains that she has quit smoking since the incident and has even developed a mild fear of flames. To make up for missing Comiket, Saki is begrudgingly volunteered by the group to go to the event and purchase items; Keiko joins Saki in order to impress Kousaka, which obviously causes problems.
During the campus cosplay event, Ohno, still being sick from the water Saki threw on her, uses this as a grand opportunity to get Saki to cosplay. Saki initially resists, but out of guilt for causing Ohno's sickness, reluctantly agrees. During the event, it's revealed that Saki is cosplaying as The President from Kujibiki Unbalance. During the audience display, Saki catches a pervert with a hidden camera taking upskirt shots, goes down and confronts him. After the pervert is apprehended by security, she returns to the stage and assumes an authoritative post - this causes widespread applause from the audience, seeing as Saki truly personified the President character, and helping her win the cosplay contest by a landslide vote. Saki is initially taken in by this and is proud to have done the cosplay, until she is brought in for questioning by the police and was requested to do so in costume, causing her to be humiliated and retract her statement.
Towards the end of the school year, many members of Genshiken are starting graduation, Saki being among them. As she ponders what the future holds for her, she looks with a slight bit of envy as Vice Chairman Kitagawa announced that she was recently proposed to. As she realized this is the last time she may be together with the Genshiken members, she starts tearing up.
During the events of Genshiken Nidaime, Saki has graduated and has since stopped visiting the club room. Saki and Makoto Kousaka have been invited to a gathering at Chika Ogiue's house. She is at first surprised at seeing an all female Genshiken. Although Harunobu Madarame had trouble identifying who the cross dresser of the group was, Saki pointed out Hato right away.
During the school festival, she stumbles upon Sue giving Madarame a kiss on the cheek. She then teases Madarame on being a lolicon, to his chagrin. Madarame asks her where Kousaka is, to which she replies he's in a fighting game tournament (and is succeeding) so she thought she'd find time to hang out with the old club members again.
As she meets up with the new and old members of Genshiken, Saki notices an interesting turn of events: Madarame is currently popular this year with the ladies (including crossdressing Kenjiro Hato), so she decides to tease him a bit. She remarks about the time they all went to his house and found all the S&M dvds in his desk; the revelation doesn't really embarrass Madarame as he originally used it as a decoy to hide his true treasured items: Pictures of Saki cosplaying. However, the attention turns towards Hato, due to his reaction and the knowledge that he's a housekeeper for Madarame, and they all wonder if he found something Madarame was hiding. Madarame is initially unworried, but the moment Hato whispered into his ears on finding the pictures of Saki, Madarame immediately panics and runs out of the room, much to everyone's confusion.
Later on, as a result of an organized effort by Kousaka, Keiko Sasahara, Hato and Susanna Hopkins, Saki and Madarame are locked in the Genshiken room together alone. Madarame asks if he was that obvious, to which Saki responds in confusion. It's at this point Madarame realizes that Saki is unaware of his feelings for her. They reminisce about the past and all of their interactions with each other, which they both remembered, but Madarame denies remembering them. Saki reminds him about the time he put cat ears on her head, and said she thought to herself "This guy likes me." Madarame was shocked she even remembered, and thought over all the moments that made him fall for her.
Madarame then confesses indirectly, "That day you had a nose hair sticking out." Saki was embarrassed and confused by the message at first, but Madarame continued. He said when he tried to tell Saki, she punched him. Saki commented that Madarame claimed to not remember that day, which he said was a lie because he wasn't brave enough to say what he wanted to say, and it was easier to pretend to forget about it. Madarame then gathered himself and exclaimed tearfully, "Back then, you had a nose hair sticking out!" At this moment, Saki finally understood what he was trying to say and responded, "I'm sorry. I have Kousaka, so I can't be with you." Madarame then asks about how peculiar she worded her statement. Saki then responded if she wasn't taken, then perhaps she and Madarame could've had a future together. With all of the weight finally off his chest, Madarame sighs in relief and comments how refreshing it is to actually be rejected. At this moment, Saki begins to tear up and reach for her hankerchief. Madarame asks her what's wrong; Saki apologized to him for trying to act like she wasn't aware of his feelings, and felt like she may have caused him so much pain in doing so. At this point, Madarame realizes how easily Saki cries and remarks on what a great time they had in the club.
- The name Saki means "blossom" (咲).