宇宙活動 / ハイテクノロジー
A helium isotope containing one less neutron than ordinary helium. Almost nonexistent on Earth, it is found in relatively large quantities on the Moon and is used for energy on Lunar bases. It is particularly valued for its use in nuclear fusion, as it does not give off any secondary radiation. There is currently a large-scale movement to try and use helium-3 not just on the Moon, but on Earth and other space bases as well.
The Tokugawa Moon Plant currently controls all helium-3 mining and processing.