Ethell is one of only four Grade 1 units in the Machine Empire and is the AI robot known as the Great Regent and the 'Brain' of the Machine Empire. She usually speaks in a stiff and polite tone, but she occasionally jokes or teases Guest. She is the de facto administrative head of the Machine Empire and oversees all administrative affairs of the empire. She possesses the Grade 1 armament 'Sleipnir'. When Sleipnir is activated, the halo on her head transforms into optical wings, allowing her to perform aerial maneuvers while firing atomic disintegration beams from the wings. However, activating Sleipnir reduces her processing power. While AI robots are fundamentally genderless, Ethell has a significantly curvaceous body and claims to be female. She enjoys physical contact with Guest.

One of only four Grade 1 units in the Machine Empire, Guillotine is an AI robot known as the secret one-man army, the 'Empire's Guillotine'. She is characterized by a bellicose personality, arrogance, and a playful nature. She particularly enjoys teasing Ethell and speaks informally to the Emperor without hesitation, though this does not mean she lacks respect. She possesses the Grade 1 armament 'Jormungand'. Jormungand is a weapon capable of form-changing between a double-handed axe and a heavy machine gun; in machine gun mode, high-strength armor-piercing rounds are continuously generated internally, firing 1,200 rounds per minute. In axe mode, high-speed diamond chains rotate constantly to cleave through any enemy, no matter how hard. She is the strongest and fastest among all Grade 1 machines, but she has the disadvantage of overheating quickly due to poor heat dissipation. She strongly dislikes Ethell clinging to Guest. Unlike Ethell, she has a somewhat petite appearance but also claims to be female.

One of only four Grade 1 units in the Machine Empire, General is the Commander-in-Chief of the Empire's military, known as the 'Shield of the Empire'. He obeys Guest faithfully and carries out his duties taciturnly. While famous in the empire for being silent and blunt, he actually has the kindest personality among the Grade 1 machines. He possesses the Grade 1 armament 'Fenrir'. Fenrir can be transformed into a sword-and-shield set, where the shield turns into an optical protection device and the sword is a plasma blade, or into a medium assault rifle that fires plasma rounds. Although slower than Guillotine, he is undamaged by most attacks due to his overwhelming armor.