Mari Yamamoto (Rental Family) Rental Family
Mari Yamamoto plays Aiko Nakajima, a Rental Family employee who carries the film's darkest storyline. Aiko is the "radical believer" in the agency's mission -- she internalizes the work's emotional cost until it breaks her. Yamamoto brought a journalist's rigor to the role, building an extensive backstory for a character the script treats as Phillip's parallel rather than his sidekick. (wonderlandmagazine)
She came to acting through journalism and method training
Yamamoto was born in Japan, moved with her family to London at age five, and returned to Tokyo at eight. She studied international relations at International Christian University in Tokyo, then moved to New York to study method acting at the Lee Strasberg Theatre and Film Institute. Before transitioning fully to acting, she worked as a journalist for The Daily Beast alongside American journalist Jake Adelstein. (wikipedia)
Her screen career accelerated with the recurring role of Hana in Apple TV+'s Pachinko (2022), followed by a main cast role as Dr. Keiko Miura in Monarch: Legacy of Monsters (2023-2024). She was cast in Rental Family in March 2024. (wikipedia)
She approached Aiko as a character study, not a supporting role
Yamamoto described her preparation in terms that echo her journalism background -- building a case file for a person rather than learning lines for a part:
"I have a journalist background, so I always approach my characters with, like, 'what are the facts?'" -- Mari Yamamoto, Wonderland Magazine (2026)
"I always make a notebook for each character I play, so it sort of becomes a history/journal." -- Mari Yamamoto, Wonderland Magazine (2026)
She constructed Aiko as bilingual with a specific upbringing, details the film never explicitly states but that informed her performance:
"I really did a thorough backstory of how she grew up, because she's bilingual." -- Mari Yamamoto, Wonderland Magazine (2026)
Her father's death during preparation gave the performance personal weight
Yamamoto read the script a month after her father passed away. The coincidence shaped how she approached the material:
"It was a month after my dad passed away...reading the script somehow made me feel like it was going to be okay." -- Mari Yamamoto, Wonderland Magazine (2026)
The Nerdist review called Yamamoto "utterly fantastic," noting that Aiko embodies the film's argument that the agency's employees are as lonely as the clients they serve. (nerdist)
She practised the Pink Lady dance for two months
One of the film's lighter moments has Aiko and Phillip performing a Pink Lady dance routine. Yamamoto trained for the scene extensively:
"I practised dancing for, like, two months, and we performed the whole song." -- Mari Yamamoto, Wonderland Magazine (2026)