Zero (X-0) Before TIDEWALL, before the four girls passed the test, there was one resonant mech and one pilot who could fly it. This is the prototype Asagiri Kaito climbed into at twenty, the machine that moved before he touched the controls, and the one Kurenai lost in the bay with him a year and a half before Tidemaw. Officially it was never piloted, never lost and never existed. The first frame that answered Kurenai had been building war mechs for five years, all of them flown by hand, when it built a new prototype for testing. The day a 20-year-old cadet named Kaito sat in it, it moved before he touched the controls. It did it again the next day, and the day after that. The engineers logged it as a fault for a week before anyone believed it. Every resonant mech that came after it, Azure Fang, Crimson Howl, White Petal and Blue Signal, was built on what Kurenai learned from this one. The resonance test every trainee takes still plays the pattern it recorded from Kaito. The test pilot's mech For three years it was Kaito's. He flew it in tests, out over the bay on its first resonant launch with Moo-jin flying escort in an old manual frame, and back to the hangar every night to run drills in the sim bay with a trainee in rig 12 who wouldn't go home. The deep test In Class 7's second year, Kurenai took the prototype out into the bay and asked Kaito to push his link further than anyone ever had. For a few seconds the readings showed something answering him that wasn't his mech. Then the prototype went into the water, and so did he. The official record lists a lost prototype and no casualties. Kaito's name was erased. Specs Designation: X-0, known as Zero Class: Classified Drive: Resonant, the first ever built Pilot: Asagiri Kaito, Pilot Zero Status: Lost in the bay Spoilers: the prototype in Season One Everything below this line happens in Season One. If you'd rather find out on screen, stop here. Its designation was never a model number. X-0 was frame zero, the machine that came before every other resonant mech, and Kaito was its pilot zero. Long before the girls became TIDEWALL's pilots 01 to 04, there was one frame and one pilot with no number at all. It never stopped working. For a year and a half, down in the trench with Kaito, it held on to the thing at the bottom of the bay, and it changed. In the finale, with Ommoros risen and the four girls drained and losing, it comes up out of the trench glowing teal. The girls think it's another monster and turn their guns on it. It ignores them, takes hold of Ommoros, and doesn't let go. Kaito says one word on the open channel. Rin's name. Then he opens his link to full depth and holds the channel open while the four girls sing every bit of their resonance down it. Ommoros dies, and the first resonant mech ever built goes down into the trench with it, still holding on.