Katsuyu: Immense Network Healing is a cooperation ninjutsu used by Katsuyu and its summoner using the link shared via the Strength of a Hundred Seal.
Firstly, Katsuyu divides its body into several smaller clones, and then each attaches itself to a person. The slug's summoner then channels their medical chakra through Katsuyu, who in turn transfers it to the wounded person, healing their wounds, restoring their stamina and chakra reserves.
This technique allows the user to heal a great number of persons simultaneously regardless of distance. While using this technique, the user is linked with Katsuyu, shown when Tsunade was able to communicate directly with the slug, had a sense of what Katsuyu was encountering on the battlefield, her reaction to Katsuyu finding Kakashi Hatake apparently dead, and later when she told Chōji Akimichi that his father was still alive after a brief pause.