The Tuatha de Danaan is undergoing repairs at Mithril’s island base. Mardukas notes that despite its incredible performance the parts are corroding too fast. Tessa goes to her office’s lounge to relax and finds Mao there, noticing with disdain the pile of beer cans and the stench of cigarettes. She tells Mao that her sloppy behavior could spread bad rumors and Mao retorts that she makes a debauchery out of every trivial thing. The argument turns sour when Tessa calls Mao a lowly subordinate and Mao fires back that all Tessa ever does is sit on a chair and give orders. Tessa argues that she could pilot an M9 far better than Mao could, and Mao demands she proves her claim in an arm slave duel using paint bullets. The loser has to streak across the beach. Tessa accepts and issues a formal challenge message which the entire base hears. Sousuke and Weber tell Mao not to pick on her captain like that, and she replies that she’ll only beat her up until she begs for forgiveness. Tessa, who was standing behind her, hears everything and they trash talk some more. Tessa walks out and tells Sousuke to follow her. Weber is so excited about the idea of Tessa being naked that he takes the entire week off. On the beach, Sousuke gets subtly told off by an angry Chidori on the phone while Tessa warms up for pilot training. Sousuke, as her coach, advises her not to try climbing into the cockpit without the ladder. As she climbs, Tessa slips and falls onto Sousuke. Sexual tension ensues to Tessa’s delight and Sousuke’s dread. Tessa finally manages to climb into the cockpit by sunset, but when she stumbles during her first step, she panics and ends up in the water.
At the bar, Weber finds a very drunk Mao and tells her that she shouldn’t have challenged Tessa like that. Mao says that she hates Tessa for being so stuck up and idealistic. Weber asks how Mao was at Tessa’s age, and she replies that she was even stupider, eventually confessing that she just feels inferior to Tessa. Sousuke and Tessa are studying the layout of the duel’s location, and she asks Sousuke if he thinks she’ll lose. She tells Sousuke that she knows the basics and plans on winning. The reason she asked him to coach her was to get opinions on her battle tactics, which amazes Sousuke as they discuss them. Sousuke tells her that she has one chance only, and Tessa says that she’ll give up if it doesn’t work. She still wants to surprise Mao no matter the outcome. On the day of the duel, Mao is waiting impatiently and notes that Tessa is late. Weber asks if she ever read Miyamoto Musashi, and Mao has no idea what that is. Tessa shows up and Mao is surprised to see that she’s using an old M6 arm slave. Tessa says that she was hungry so she went for a bite, further irritating Mao. As Sousuke fires the starting gun, Tessa tells Mao not to hold back, which she’s planning on doing. Tessa hides in the forest and Mao fires several shots at her, but Sousuke declares them as misses because the trees prevented direct hits. Mao protests that in live combat the shots would have penetrated the trees and Sousuke reminds her that this isn’t live combat. Tessa fires back but hits the rocks and Sousuke tells Mao that in live combat her sensors would have been damaged by that shot. Grumbling, Mao chases after Tessa. Tessa is struggling not to fall down and notes the intensity of the battle which Mao regularly experiences. She nearly admits defeat when Sousuke encourages her to go on. Mao tracks Tessa once more and is about to fire when the M6 disappears from her sensors by cloaking. Mao activates the M9’s light sensitive sensors and finds her. She lunges at Tessa and the latter uses a flash to overload the M9’s sensors, blinding Mao and causing her to lose balance. Tessa gets up front and empties her clip at Mao, winning the duel. Mao bitterly admits defeat, and she and Tessa apologize to each other. Mao is glad that she lost, and Tessa says they’ll never do this again. Weber asks about the loser’s penalty, and promptly gets kicked in the face by both girls.
A nice character development episode for Tessa and Mao. We get to see the age-old rivalry between different branches of the military settled with an arm slave paint ball fight, and it helps to strengthen Tessa and Mao’s already good friendship since we see Mao casually hanging around Tessa’s office in the beginning of the episode. Tessa also got to spend some quality time with Sousuke during her training and certainly isn’t shy about enjoying it as much as she can. Chidori has some strong competition.