During reformation of domain duties by Nariakira SHIMAZU, lord of the domain, Tomozane forged close ties with royalists of other domains, as a rusuiyaku (a person representing the master during his absence) of Ozaka hantei (a residence of the domain in Ozaka [Osaka] maintained by daimyo), thus playing an active role as a younger reformist.
藩主島津斉彬の藩政改革のもと、大坂藩邸留守居役など、諸藩の志士との交流を重ね、若手改革派の一人として活躍する。