Toner, image forming apparatus, and image formation method

A toner comprising toner particles, wherein

• the toner is used for a non-magnetic one-component development,
• the toner particles each include a toner mother particle containing a binder resin and an external additive attached to a surface of the toner mother particle,
• the external additive includes fluorine-containing particles,
• the fluorine-containing particles contain a fluorine atom at least in surface layers thereof,
• an amount of the fluorine-containing particles is at least 0.10 parts by mass and no greater than 0.20 parts by mass relative to 100 parts by mass of the toner mother particles, and
• when ultrasonication is performed, a residual amount ratio of remaining fluorine-containing particles is at least 0% by mass and no greater than 20% by mass relative to the amount of the fluorine-containing particles attached to the toner mother particles before the ultrasonication, the ultrasonication being application of ultrasonic oscillation at an output of 200 W, a frequency of 28 kHz, and an amplitude of 25 μm for 5 minutes in 500 mL of a water-based dispersion containing 5 g of the toner and 50 g of a nonionic surfactant.