Hotarubi

The Hotarubi grounds are shown to resemble a traditional Japanese garden surrounded by trees blossoming in purple flowers. A Japanese-style house can be seen in the distance. It rains all-year round, the gentle sounds of rain accompanying the quiet air.

The MC describes it as "rain-scented air tinged with an odd sense of melancholy" and remarks the place to be "pretty magical" and "wistful." It is also covered in thick mist that causes "many first-time visitor find themselves lost upon entrance" according to Professor Moby, who serves as the house's advisor.

The interior is described to be beautiful, although it "is in sore need of a renovation" according to the vice-captain, Haku Kusanagi. The entrance to the captain's room is a sliding door, matching the traditional Japanese style of the dormitory. There is also a reception room, mainly purposed for serving tea and sweets for guests.

Deep inside the grounds, there lays a lake shore hidden in thick mist. Students can row across the lake in one of the small boat at the harbor. On the other side of the lake, there is a cave that has dimly lit and damp corridors. Along both sides of these corridors are cells, containing anomalies.

According to the MC, the place almost resembles a prison. Behind a massive metal door is the sturdy cell Lyca Colt was previously imprisoned in. Throughout the story, it is implied multiple times that Lyca was badly mistreated and neglected during the two years he was confined in his cell.

According to Haku, this form of imprisonment could happen to any of the ghouls inhabiting Darkwick if they don't cooperate or behave or are "deemed as a threat to humanity". It is later revealed that this cave/facility used to be managed by one of the lost house, Ultio, but is now being run by Darkwick to "keep anomalies deemed too dangerous for human contact."

Not much is known about Hotarubi's past, except that one of its ghoul members, Zenji Kotodoma, succumbed to his injuries during the events of The Clash, and that Haku Kusanagi transferred from Frostheim to Hotarubi. Hotarubi was also part of the dissidents.

Missions in Hotarubi often have a theme involving the culture of Japan.

The students of Hotarubi are known to be one of the finest in Darkwick Academy, holding a pristine reputation amongst students and professors alike. The residents are typically "busy with their own creative pursuits" and "rarely venture out without reason." Despite most of them being holed up in their rooms all day, they are shown to be very welcoming to guests and "seem to have a lot of respect for each other's time and space."

Hotarubi students mostly specialize in anomalies endemic to Japan, meaning they focus on anomalies that regularly appear in Japan. Although their slim field of expertise allows a relatively peaceful and calm school life, the captain, Subaru Kagami, states that it usually makes it harder for the residents of Hotarubi to leave significant academic marks.

“Artsy. A lot of them work in creative fields. That's probably why they're all a little unique. They feel kinda fake though, you know? The professors are always harping on about Hotarubi being full of model students. Gifted, talented, perfect little angels... they've gotta be hiding something, right?!”

– Kaito, About Hotarubi

• Hotarubi (蛍火) means "firefly's light" when transliterated from Japanese.

The house's english name, Firefly's Light, is part of the chapter title of Episode 5 Chapter 3.

• In Episode 5, it is revealed that its members are referred to as Hotarubians.