Mute Spellcaster. Yuuko Akatsuki is mute. but she can fake the verbal components of her spells through sign language. doing this requires both her hands to be free 

Spellcasting. The Yuuko Akatsuki is a 3rd level sidekick that is treated as a 5th-level spellcaster due to being a spellcaster prior to becoming a sidekick. Her spellcasting ability is [Intelligence] (spell save DC 13, +5 to hit with spell attacks). Yuuko Akatsuki has following [Wizard] spells prepared:
Cantrips (at will):  [Firebolt[ [Ray of Frost] [Shocking Grasp] [Message]
1st level (4 slots): [Burning Hands] [Detect Magic] [Comprehend Languages] [Chromatic Orb]

2nd level (3 slots): [Web], [Suggestion] [Shatter]

3rd level (2 slots): [Fireball], [Hypnotic Pattern] [Sending]

Innate Spells. Yuuko Akatsuki casts the Following Spells innately without expending a spell slot or using components, Her spellcasting ability is [Intelligence] (spell save DC 13, +5 to hit with spell attacks)..

Cantrips (at will): [Light], [Prestidigitation]
1st level (1/Long Rest): [Mage Armor]