# TBS drama LOST10 casting updates

> Live situation record from CLSTR: https://clstr.news/situations/tbs-drama-lost10-casting
> Updated: 2026-08-20T21:45:23.000Z. Sources: 8. Developments: 3.

In late July 2026, TBS announced that actor Yokohama Ryusei would headline its new Friday night drama “LOST10,” set to debut in October. The series, written by Okudera Sado and directed by Tsukahara Ayuko, follows detective Komatsu investigating a mountain rescue incident in Hokkaido, and emphasizes themes of doubt and truth. Yokohama described the drama’s core message as “doubt everything.”

A week later, TBS confirmed that Oguri Shun would join the cast in a regular role as Nao, a freelance insurance investigator who alternates between ally and adversary to Ryusei’s character. This marks Oguri’s first regular appearance in a commercial TV series in five years. The production involves extensive on-location shooting across Sapporo, Yoichi, and Asahikawa.

In August, further casting was revealed, including Ann Nakamura as Aya, a junior high school teacher among the accident victims, and Marie Iitoyo as Tabata, a mountain climbing guide. The plot centers on the “Shikaradake incident,” a mountaineering accident that triggers interconnected stories. Reports indicate that TBS had been pursuing Yokohama for the lead role for three years due to his professional reputation.

## Timeline

### 2026-08-20: Ryusei Yokohama to star in TBS suspense drama ‘LOST10’

Ann Nakamura and Marie Iitoyo join Ryusei Yokohama and Shun Oguri in the upcoming TBS suspense drama ‘LOST10’, a story centered on a mountain climbing accident in Hokkaido.

2 sources. https://clstr.news/cluster/ryusei-yokohama-to-star-in-tbs-suspense-drama-lost10

### 2026-08-06: Oguri Shun joins Yokohama Ryusei in TBS drama LOST10

Oguri Shun returns to TV in a regular role, co‑starring with Yokohama Ryusei in TBS’s October drama LOST10, a Hokkaido‑set human suspense series.

4 sources. https://clstr.news/cluster/oguri-shun-joins-yokohama-ryusei-in-tbs-drama-lost10

### 2026-07-30: Yokohama Ryusei Leads TBS Friday Drama “LOST10” Starting October

Yokohama Ryusei heads the TBS Friday drama “LOST10,” premiering in October at 10 p.m., scripted by Okudera Sado and set in Hokkaido around a mountain rescue incident.

5 sources. https://clstr.news/cluster/yokohama-ryusei-leads-tbs-friday-drama-lost10-starting-october

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Cite as: TBS drama LOST10 casting updates. CLSTR, https://clstr.news/situations/tbs-drama-lost10-casting