I asked Hitomi about these after reading this article on Stars & Stripes website. She said she’s never heard of them, nor seen them before. However, they’re apparenlty pretty common in parts of Japan. The article describes the げじげじ as:
Big. Quick-moving. More than 10 pairs of legs … having just one of these endearing qualities is usually enough to make an insect unwelcome, let alone all of the above, says Hideomi Kakimoto, a Yokosuka base environmental engineer.
But “geji,” or household centipedes, are known as “good bugs” in Japan, as their ninja-like maneuvering (and, cringe, their ability to jump) allows them to hunt other household pests like cockroaches and clothing moths.
Wikipedia says that geji are even sold in Japanese pet stores.
“They do look scary,” Kakimoto said. “But they are good bugs.”
Another “good bug” is the ashi daka gumo, which is a huge spider.
Frightening in size and speed, these are excellent cockroach killers and are harmless to humans, Kakimoto said. The spiders don’t even make a mess, as they don’t build webs, relying instead on high-speed chases to snag their prey.
Our daughter Rei loves insects. She has no problem having an African millipede crawl right up her arm. But personally I’d probably step on either one of these the second I spotted one in my house.