Denroku Sukegawa serves as the 73-year-old maintenance worker at Kissuisō hot spring inn, managing janitorial tasks and boiler operations. His employment spanned the inn's entire existence, from founding until closure. This enduring role made him a bedrock of institutional knowledge at Kissuisō, earning him the affectionate staff nickname "Mame-jii" for its playful nod to a renowned bean snack brand resembling his name.

Beneath a rough exterior, Denroku harbors a quietly nurturing disposition toward younger colleagues. He routinely aids them behind the scenes—especially when their well-meant initiatives might draw reprimand from the strict proprietor, Sui Shijima. This covert support underscores his dual loyalty to Kissuisō's heritage and its people, always championing their development.

His subtle influence shines when he reveals a hidden cache of historic uniforms crafted by Sui to Ohana Matsumae. This pivotal act empowers Ohana and Nako Oshimizu to rejuvenate the inn’s appeal by reviving the vintage attire, delighting guests. Denroku further safeguards Kissuisō's legacy through his meticulous upkeep of its daily business journal, ensuring operational continuity endures in record.