Three years ago, Kou and Leann were assigned partners for a mission. Kou was surprised: "A... A woman?" and Leann replied, "I've got a name." The senior officer told Kou, "Her survival abilities may be higher than yourself." Kou's lack of response prompted Leann to ask, "Is there something on my face?"
However, during the mission, Leann misjudged the number of men the other side had. Kou volunteered to stay behind and distract the enemy while Leann got away. Leann said the idea was suicidal. Kou, though, told her to trust him, and if they got out alive, she would owe him a drink. She said she would think about it.
Leann was later promoted because of the mission's success, though she tried to credit Kou for the outcome. Kou, however, said it was her abilities that got her promoted. He then reminded her of the promise they made. Leann was confused, and Kou said, "You owe me a drink."
As Kou's superior, Leann gives him orders and assignments. Kou obviously likes her, and in the game, one of his main focuses seems to be meeting back with Leann for their drink.
One year ago, Leann was informed by her superior officer about Mikado's solar energy plan and how they were involved in "surgical enhancements." The superior officer said that this mission would be their most difficult one yet, but Leann was certain "he", meaning Kou, could handle it. Six months later, Leann gives the assignment to Kou, with the orders that he is to get a full-body tattoo to go undercover. Kou's mission is to watch over Dominique Cross and prevent Mikado Group from getting her. If he fails, he must kill Dominique.
At the very beginning of The Bouncer, the woman at her computer listening to the news is Leann. Leanne receives an encrypted message saying that Mikado has sent its special agents to kidnap Dominique. Leann is shocked that Mikado has already struck.
Kou keeps in touch with Leann throughout the game using his cell phone and communicator. If you use Sion or Volt for most of the game, then Leann remains a mystery woman, even more than Kaldea. The only times you see her are at the beginning of the game (but never her face) and her face in shadow in the fighter plane.
Right after Dominique has been kidnapped, Volt says that her kidnappers were Mikado's Special Forces. Sion wants to go to Mikado, but Kou tells Sion he has connections. He calls Leann on his cell phone. In Kou's scenario, you actually hear their conversation, whereas in Sion's or Volt's, it's one-sided. Leann criticizes Kou for allowing Dominique to be kidnapped, then tells him how to infiltrate Mikado: the bouncers must take a special Mikado train leaving in half an hour, which is carrying fuel for the shuttle launch. She tells him she'll provide him with back-up at Orage. He thanks her.
If you use Kou on the train, he keeps waiting for Leann to arrive. After Echidna is defeated, Leann finally shows up in her fighter jet. She gets in front of the train and begins shooting at it. Kou, of course, isn't too thrilled with all the jostling (he tells the "woman" to be "more gentle"), and he's especially upset when the train's brakes go out, and it's about to crash into the station ("Can you say, "overkill"!?")
Later in the game, the bouncers need to reach Galeos and rescue Dominique. It launches, and Kou frantically wonders where Leann is. Leann appears, leading the "LUKIS" jets, and they begin to shoot the Galeos. She tells Kou that all she can do is slow down its flight to buy the bouncers time to board it. Leann also advises Kou on how to reach the Galeos after it has lifted off, by using the air carrier nearby.
After Dauragon is killed on the Galeos, depending on the bouncer you chose at certain points in the game, you may get Leann's ending. Leann sends a transmission to the Galeos telling the bouncers that she believes they are alive. She informs them that the shuttle is about to crash into the satellite. The shuttle, however, splits into two parts, and the aft portion will return to Earth, so the bouncers must reach the back of the shuttle.
To receive this ending, you must choose Kou after the bouncers defeat Dauragon for the first time (when he is fighting one-handed), then choose Kou or Volt in the hallway of the Galeos when you fight the black panther.
As the bouncers and Dominique watch the satellite and shuttle explode, Kou speaks to Leann, who tells him he did a good job and a long vacation will be waiting for him when he gets back. She says she will contact him about his future assignments. Kou comments that she really knows how to use a man.
Back at FATE, it's Kou's shift. As he heads out, he receives another call from Leann. She says that even though the satellite was destroyed, Dominique still needs to be watched. They've found a replacement for Kou so he can go on vacation. Kou, who has grown fond of his friends and Dominique, requests to stay in his current assignment. Leann says she thinks that will be okay but asks him why he had a "change of heart." He tells her it's just a feeling he has. She says she'll tell higher command about his request, but she reminds him not to get personally involved with his assignment.
Later, towards the end of Kou's shift, the bar closes for the evening. Leann contacts him again telling him to go to the central plaza. Kou reluctantly goes, and when he reaches the fountain, Leann appears. She says she has orders from high command to fight him. They fight.
If you defeat Leann, Kou demands to know what this was about. Leann says that headquarters wanted to test him. If he couldn't beat her, they didn't want him watching over the target. Kou remarks that they have little faith in him, to which Leann reminds him that if had been on top of things, the whole situation wouldn't have happened. When he asks what happens now, Leann gives him a thumbs-up and tells him he passed. She says, "Ja ne" and walks away. Kou calls out to her, saying that he hasn't seen her for a while, and since she's here, why don't they... Without turning around, Leann reminds him it's against regulations to personally involved with one's assignment. As she leaves, Kou says it's a tough job and winks.
If you lose against Leann, Kou asks why Leann fought him, and Leann gives the same explanation. Kou, a little down, asks what will happen now. She says, "You're relieved of your assignment, of course." She turns and starts to walk away, then stops and, without turning around, says "... is what I'd like to say..." Leann says that Kou will keep his current assignment. Kou asks if that's really okay. She replies that it was his fault Dominique got kidnapped, but he managed to solve the problem with Mikado. Kou smiles and tells her he thought personal feelings weren't supposed to be involved. Leann tells him not to get cocky and leaves.