Fairies are simple but expressive beings that exist in large numbers in Gensokyo. Daiyousei is one of the more powerful ones. Her personality is the same as the other fairies: cheerful and prank-loving. She has an unexpected tendency to act without thinking about the consequences.

She is called Daiyousei because it means greater fairy in Japanese. She is nicknamed Dai and can often be spotted together with another fairy named Cirno.

The fairies in Gensokyo all love playing pranks. Daiyousei is included, of course, but the fairies around her play even bigger pranks, so it makes it seem like Daiyousei does not play that many pranks herself.

In Phantom-Human Maid for a Day?!, Daiyousei and Cirno are playing at the Misty Lake as usual when they spot Youmu, Flandre, and Meiling in maid outfits. Cirno thinks something fun must be going on, so she heads to the Scarlet Devil Mansion, and Daiyousei rushes to follow her. Then, they suddenly hear a deathly shriek! The two tremble as a mandrake runs right past them.

Thanks to Youmu, the mandrake was returned to its proper home. When Cirno saw this, she thought of a terrifying prank: she wanted to pull out ALL the mandrakes in Patchouli's magical garden! "Don't do it, Cirno!" Daiyousei pleaded, but Cirno paid her no heed... Pluck, pluck, pluck she went, and once again, deathly shrieks rang through the Scarlet Devil Mansion.