Kousai (a Touhou LW original) refers to a plague of locusts. It seems a fitting temperament for Wriggle, seeing as she's an insect youkai capable of manipulating insects. She's endowed with Fire Phase, because she likes summer, and Star Essence, since she can produce light. The formless and passionate Fire Phase resists Wood Phase, because wood feeds fire, but it is weak to Water Phase, because water dampens fire. The diverse and uncooperative Star Essence resists the cooperative and indecisive Moon Essence, but it is weak to the charming and arrogant Sun Essence.

Wriggle Nightbug's ability as an insect youkai. She's able to freely control insects who gather and await her orders. It's said insects like the firefly avoid being caught thanks to their beauty and are thus highly likely to live for a long time. In doing so, even regular insects eventually become insect youkai. It must be noted that insect youkai are not particularly strong, although it's possible that they were stronger in the past. Humans should still be careful not to underestimate insects unless they want to become their next meal. An army of ants can even defeat an elephant. In a time gone by, youkai with insect-like appearances were common. Back then, insects posed a far greater threat to crops and human life than they do today. Many stories of dangerous bug youkai have been passed down the generations, such as the oomukade (giant centipedes) that terrorized even dragons and tsuchigumo that plagued youkai hunters with fevers. Many Japanese kanji characters pertaining to dragons contain the kanji radical for "mushi," which means "bug," "insect," "worm," or any other creepy-crawly. Perhaps in that time, it was more natural to envision an insect when thinking about a terrifying youkai. "Mushi" was also a more complicated and far-reaching classification than it is today. It stretched beyond common insects, arachnids, and centipedes to include invertebrates and reptiles. Even systems related to human cognitive functions were no exception. This led to the complex system of two separate Japanese kanji characters that share the same reading, "mushi." However, as time went by, the simpler of the two symbols came to represent common insects, arachnids, and centipedes, among certain others. Creatures with supposed mystical natures came to be categorized by biologists and entered the realm of the mundane. With advances in science, insecticides and pesticides spread, and the threat insects posed to humans diminished. Whether Wriggle wishes for the insect youkai to return to their former glory is unclear, but she is not the only one living in Gensokyo. There may even be an insect god. Perhaps the day when the insects regain their strength and swarm down on humans is not so far away...