Throughout the series, Hotaru Imai has created a varitey of inventions. Below is a list and links to Hotaru's various creations.
Snapping Turtle Mail
This invention is shaped much like a windup toy in the shape of a small turtle. The start it up, the user winds the key on the turtle's shell. It is used to deliver mail.
"It takes one week to deliver mail anywhere. Once it gets hold of a letter, it won't let go until the addressed person has recieved the letter. There is no expression delivery option." - Hotaru Imai
Egg Helmet (Tamago Helmet)
Fying Swan Scooter
There are two Hoof Gloves; the Deer Hoof Glove and its sister, the Horse Hoof Glove.
Hotaru created these earmuffs for the purpose of Mission: Human Sea. They are meant to be used as a type of walkie-talkie or cellphone. They are shaped like normal earmuffs with the ear covers being panda shaped and colored. They come with a microphone, and a ringtone. The ringtone begins as "Panda, Panda, Panda no Dance". The earmuffs can be turned on and off.
Muscle Enhancement Stickers
Caterpillar Sleeping Bag (aka Wormies)
Pigula 3 is Hotaru's mecha for the exhibition at the Alice Festival. It is capable of transforming into a bird mecha for flight. The bird transformation is called Pigbird. There are possibly two previous mechas by the names of Pigula and Pigula 2.