Basil is a wild and mischievous apprentice Thunder Fairy who uses a drum to generate lightning as part of his weather-manipulating magic. He often delights in using his abilities for playful pranks rather than concentrating on his formal training. His closest friend is Cinnamon, a hail fairy apprentice, and the pair frequently collaborate on causing trouble, usually earning them scoldings from authority figures among the season fairies.

Physically, Basil has light skin, blue eyes, and spiky blonde hair. Like other Season Fairies, sections of his hair form rounded circular shapes. He possesses two small, round, transparent wings with a blue-turquoise hue. His attire includes a pointed hat, a black and light yellow tank top featuring a black lightning bolt, black and yellow-striped shorts, thong sandals, a black neck bandana, black ringlets around his wrists, and a golden cuff on his left ear. He is sometimes depicted wearing a light yellow fanny pack; it remains unclear if he uses this to store his drum like some other apprentice fairies.

Basil arrives in the human world alongside Cinnamon after the initial trio of apprentice fairies, Sugar, Salt, and Pepper, have begun their training. Their presence further complicates the life of Saga, the human protagonist who can see the season fairies, as their penchant for mischief and pranks on humans adds to Saga's disruptions. In one early incident, Basil and Cinnamon's irresponsible behavior temporarily influences Sugar during a period of estrangement between Sugar and Saga, highlighting their initially carefree approach.

The OVA, set four years after the main series, confirms Basil's continued presence and involvement with the other fairies. During this time, the fairies collaborate on creating their own play, indicating ongoing group activities. His role remains consistent as a supporting character defined by his energetic prankster nature and his strong friendship with Cinnamon.