Keys to the Heart

Keys to the Heart is a 2018 South Korean comedy-drama film directed by Choi Sung-hyun.^[2] The film stars Lee Byung-hun, Youn Yuh-jung and Park Jeong-min.^[3][4] The English translation of the original film title is That's my World.

Keys to the Heart
Theatrical release poster
Hangul	그것만이 내 세상
RR	Geugeonmani nae sesang
MR	Kŭgŏnmani nae sesang
Directed by	Choi Sung-hyun
Written by	Choi Sung-hyun
Produced by	Ju Seoung-hwan Yoon Je-kyoon
Starring	Lee Byung-hun Youn Yuh-jung Park Jeong-min
Cinematography	Hong Seung-hyuk Kim Tae-sung
Edited by	Kim Sun-min
Music by	Hwang Sang-jun
Production company	JK Film
Distributed by	CJ E&M
Release date	January 17, 2018 (2018-01-17)
Running time	120 minutes
Country	South Korea
Language	Korean
Box office	US$25.8 million[1]

Plot

The film follows the emotional journey of two estranged brothers as they reconnect and find healing through music and family.

The story centers on Jo-ha (played by Lee Byung-hun), a washed-up boxer who has spent most of his life on the fringes of society. Down on his luck and with nowhere to go, Jo-ha reconnects with his long-estranged mother In-sook (Youn Yuh-jung), whom he has not seen in over a decade. To his surprise, she is now caring for Jin-tae (Park Jung-min), his younger half-brother, who has savant syndrome and is a gifted pianist with an extraordinary musical talent but limited ability to navigate the world on his own.

Forced to live under the same roof, Jo-ha initially struggles to adapt to his new environment and feels awkward around his intellectually disabled brother. However, as time passes, he begins to soften and form a bond with Jin-tae, discovering both the pain and beauty of family connections he had long rejected. As Jo-ha confronts his own failures and lost dreams, he becomes inspired by Jin-tae’s innocence, resilience and musical passion.

Cast

• Lee Byung-hun as Jo-ha
  • Park Sang-hoon as young Jo-ha
• Youn Yuh-jung as In-sook
• Park Jeong-min as Jin-tae
• Han Ji-min as Han Ga Yool
• Choi Ri as Soo-jeong
• Hwang Seok-jeong as Department Head Kang
• Jo Kwan-woo as Moon Seong-gi
• Oh Hye-won as Bok-ja's entourage
• Baek Hyun-jin as Dong-soo
• Moon Sook as Bok-Ja (Special Appearance)
• Kim Sung-ryung as Madam Hong (Special Appearance)

Production

Principal photography began on June 6, 2017, and ended on August 27, 2017.^[5][6]

Reception

Critical reception

The film explored themes of forgiveness, reconciliation and the power of family, using heartfelt performances and moments of humor to tell a moving story about second chances. With a strong emotional core and standout performances, especially from Park Jung-min as Jin-tae, the film was well received for its sincere portrayal of disability and familial love. It became a moderate box office success in South Korea and contributed to ongoing conversations about neurodiversity in mainstream cinema.

Yoon Min-sik of The Korea Herald called the characters and plot "generic and predictable" but praised the acting performance of the film.^[7]

Shim Sun-ah of Yonhap News Agency praised Choi Seong-hyeon for handling family relationships with the utmost sensitivity and drawing good performances out of his actors.^[4]

Box office

According to figures provided by the Korean Film Council, just 3 weeks after its release, the film had surpassed 3 million viewers.^[8]

Awards and nominations

Awards	Category	Recipient	Result	Ref.
2nd The Seoul Awards	Best Actor	Lee Byung-hun	Nominated	[9]
	Best Supporting Actress	Kim Sung-ryung	Nominated

Music pieces

The following music pieces appeared in the film:

• Mozart Piano Sonata No.11 in A major 'Rondo Alla Turca' K.331
• Beethoven Piano sonata No.14 in C sharp minor 'Moonlight' Op.27-2 3rd Movement
• Chopin Piano Concerto No.1 in E minor Op.11 3rd Movement
• Brahms Hungarian Dance No.5 in G minor
• Tchaikovsky : Piano Concerto No. 1 in B flat minor, Op. 23

Remake

Philippine adaptation of the film was released in October 2023, Netflix.^[10][11]