Ran Hoyume serves as a core member of the Time Lease team operating in Osteandel City. She works alongside colleagues such as Harubou and 2-3 within a business that leases advanced technology and robots. Her daily responsibilities include assisting clients and countering threats posed by the rival Skull Lease company.

Ran maintains a close friendship with Sokkyu Gou, the orphaned maintenance worker at Time Lease who secretly operates the psychic hero Ippatsuman. Initially unaware of Gou's dual identity, she routinely contacts him for help when the Clean Aku Trio from Skull Lease disrupts operations, unknowingly summoning Gou to transform into Ippatsuman and utilize his undersea lab and psychic robot against threats. Ran develops unreciprocated romantic feelings for Gou, noticed by others in their circle though Gou himself remains oblivious.

The arrival of Time Lease's new managing director, Haruka Hoshi, triggers significant change. Ran and her colleagues gradually deduce Gou's secret identity after his psychic robot is destroyed and he suffers critical injuries during a Skull Lease trap. Gou later confirms his identity to the entire team, who collectively vow to protect it. However, Ran experiences growing emotional distance from Gou as he collaborates more closely with Haruka, who assists him with a new enhanced combat suit and the Sankan-Oh mecha. This partnership strains their relationship, culminating in Gou's temporary departure from Time Lease and a staged marriage to Haruka as part of a ruse against Skull Lease.

Conflict escalates when Skull Lease, under the alien entity Con Cordo, captures and tortures Ran to obtain psychic robot data. She is rescued during the final confrontation where Gou and the Time Lease team defeat Con Cordo and free Haruka from mind control. Following these events, Ran participates in repairing Time Lease equipment, including the Tokkyu-Saurus mecha, while Gou assumes a technical directorship at the company.