Kairagi are more deadly when founds in pairs. When there are two, killing one will trigger their Heal attack and also empower the remaining Kairagi, adding extra combo attacks when infused. In these places, it's best to try to kill them both at the same time, use Freeze to delay the heal, or to focus one down first so the other does not heal anything.
Kairagi are immune to CC fromskills, which make them particularly difficult to group. They also move a lot during their attacks, making them split apart easily. Using Freeze is a good way to keep them together longer.