After Katamori's arrival in Kyoto, HIROSAWA was assigned to koyokata (the section of local domain which is in charge of dealing with all works related to the bakufu central government and the Imperial seat) to promote interactions with Kugyo (Court nobles), feudal retainers of domains, and Shinsengumi (a group who guarded Kyoto during the end of Tokugawa shogunate).
容保上京後は公用方に任ぜられ、公卿、諸藩士、新選組などと交流を持った。