Mystery of Lilith

Short Summary
''Osamu and the others brings Xeno and Lilith to Shizuka Marine World to teach Xeno and Yūma on how to swim. Later, Giev's trion soldier attacks them, forcing Lilith to reveal her true identity.''

Long Summary
Charon and Giev discuss the failure of their last plan. Charon suggests taking Osamu out.

The gang go to Shizuka Marine World, getting the entire area to themselves thanks to Usami’s efforts. Lilith and Chika are overjoyed that Xeno seems to be getting along with Osamu. The boys talk about water while they stretch, and Osamu thinks that he saw someone but no one else has. Meanwhile, the girls are still busy.

Back at Tamakoma, Konami angrily complains about Tamakoma Second being able to go to the water park before deciding to go to Border’s own pool for “training.”

Osamu looks for the person he thinks he saw while the girls pick out their swimsuits. Chika thinks she sees someone, and they quickly rule out the possibility of a trion soldier before checking outside and seeing Osamu walking towards them. Osamu is accused of peeping on the girls, and Usami even teases him for it. The girls finally get changed and the six of them enjoy the park. Osamu continues thinking of the presence from earlier, and goes looking for them.

At Border, Kitora walks into the training pool and finds Konami, Arashiyama, Kumagai, Nasu, and Satori sitting on pool chairs in bright swimsuits. They try to make Kitora to join them, but it is the arrival of Karasuma (and Kizaki) that finally seems to convince her.

Osamu finds the figure he saw earlier and chases them around before he is attacked by them. It turns out to be a liquid trion soldier, and the gang fight against it. Usami reveals to the higher ups that Chika’s side effect didn't trigger against it, and all of them need to find the core of this trion soldier to defeat it. They shut off the pipes to lure the main body of the trion soldier to them. The combatants await the soldier on the roof and almost take it out, but when Chika fires her shot explodes back at them and causes Osamu and Chika to detransform.

Lilith stands before it and transforms before defeating it in one beam. Charon takes Osamu hostage and Giev tells Lilith that it is unwise for her to attack.

Characters in order of appearance

 * Charon
 * Giev