Who is the main character in Four Hands, Two Sonatas? Song Kang got top billing — Lee Jun-young got the origin story
The billing block and the plot engine are not in the same place in this drama, and the gap between them widens as it goes. By the midpoint they're barely in the same show.
On paper the answer is simple. Song Kang is first-billed on tvN and Netflix materials, plays Kang Bi-o, and the series is built as his comeback vehicle — his first acting work in two years, after roughly 18 months of mandatory military service. MyDramaList lists him and Lee Jun-young as co-leads with Jang Gyu-ri as supporting. The camera follows Bi-o.
The character the show is pointed at
Bi-o is the number one student at Korea Arts High School, a childhood prodigy who practises ten hours a day. His problem is not talent. He is the illegitimate son of a wealthy musical family, chasing recognition from his grandfather Kang Seung-woon (Jung Jin-young), a conductor who has no time for either his daughter or her son. At school he is bullied by classmates Yoon Han-rim and Jang Seok-hwan. His mother Kang Ji-hye (Yoon Se-ah) is a former ballerina raising him alone.
Song Kang trained on piano extensively for the part and was candid at the press conference about coming back cold.
"It was my first script reading in a long time, so I was very nervous," Song told reporters, as quoted by the Korea Herald in 2026.
Director Park Hyun-seok, best known for Stranger, described the premise as classical repertoire crossed with a coming-of-age story.
The character the plot is made of
Choi Jeong-yo is the one with the backstory. A piano genius who gave it up because of his family — an alcoholic father, Choi Gi-taek, a former piano tuner; an older street friend, Jo Hyun-cheol, keeping him fed; a loan shark, Director Kim, working the neighbourhood — he transfers into Korea Arts High School only after hearing Bi-o play at a concert reopens something he'd shut down.
Everything that drives the series after episode 5 comes from him:
- Prague — kidnapped by paid drivers before the Harmonie Competition final, shot during the escape, left in a lake.
- Nine years — presumed dead by the entire classical music world, while Bi-o runs a private investigation for five of them.
- Luca Domenico — the identity he returns under, as a conductor, at a conducting competition.
- The right hand — nerve damage from the shooting ended his piano career.
- The amnesia — an act, confirmed in episode 7, staged to get close to Bi-o's mother.
Where the answer flips
Episodes 1 to 5 are Bi-o's: his ranking, his fear of being beaten, his injured finger, his win. Episode 6 jumps nine years and hands the drama to Lee Jun-young, who plays two versions of the same man in the same scenes — the boy Bi-o remembers and the composed European conductor who greets him in English and pretends not to place him. Leisurebyte's 2026 review of episode 7 credited him with carrying the episode outright.
Bi-o is the point of view. Jeong-yo is the plot.
The working answer
Kang Bi-o is the protagonist — it's his ambition in episode 1, his grief in episode 6, his anxiety being treated in episode 8. Choi Jeong-yo is the one the story is about: the disappearance, the return, the revenge that may not be aimed where it looks. Hong Jae-in, the viola major with the exceptional ear, is the third lead in the cast list and the one who registers what both men are actually playing.
For the record: the Korean title is 포핸즈 — "Four Hands" — a piano duet for two players at one keyboard. The English title adds the second half. Two sonatas, two soloists, one bench.
Previously we wrote: Gilmore Girls made the NYT best shows of the century, and Alexis Bledel's interview admits Rory was nearly someone else's
