Mr. Holmes (2015 Bill Condon)

Info here. Souce novel by Mitch Cullin - 'A Slight Trick of the Mind' - was published in 2005, and the fact the author's partner is Japanese, and they share residences in both countries, perhaps suggests the Japanese element in the novel. The book was adapted by Jeffrey Hatcher, author of mainly historical stuff like The Duchess (Kiera Knightley and Ralph Fiennes) and an episode of the badly judged Upstairs Downstairs remake.

Dave Elsey was the makeup artist responsible for aging Mr. McKellan.

Could think of no good reason why it was shot in widescreen.