Hotaruika/ホタルイカ is a small squid with a body length of about 5-7 cm. It has 700-1,000 luminescent organs on its body, which emit a blue light when stimulated, resembling the glow of fireflies. Due to this appearance, it is called Hotaruika/萤火鱿/螢烏賊/ホタルイカ, which means "firefly squid" in Japanese. It is mainly found along the coasts of Japan.
Hotaruika is commonly used in dishes such as "Sumisoae" (vinegared miso dressing), "Okizuke" (marinated in soy sauce), and dried seafood. Since it is consumed with its internal organs, it has a distinct savoury and rich flavour.