After watching this beautiful film I was blown away by the fact that this was Kim Go Eun's first ever acting role. Playing a younger (she is 21) role as a schoolgirl, Han Eun Gyo, she is incredibly natural and at ease in the part. Park Ha ll creates the elderly 'grandpa' figure Lee Juk Yo but is actually a revered poet laureate who has mentored a bitter, jealous Seo Ji Woo played convincingly by Jim Mu Yeol.
The chance meeting of the ML and FL is a catalyst as they create a relationship based on unspoken needs. For Han Eun Gyo, lacking affection at home, the 'grandfather' allows her to express her kindness and makes her happy and a little bit competitive with Seo Ji Woo to gain Le Juk Yo's affection. For Le Juk Yo he is transported back to a more youthful time and creates a romantic fantasy that he then channels into a beautiful story.

The plot is about art and literary posturing. It is about how, even when we age, the mind remembers our youthful selves. It is for each character about yearning.
Yes there is a sex scene. The depiction is summed up by the rhetoric question, mid coitus, by Han Eun Gyo "do you know why teenage girls have sex? It is because we are lonely". Reflecting back to Seo Ji Woo his own words and summarising it is just sex.

Loneliness is an underlying theme but the creative fantasy of the poet for the young girl is set in a dreamlike idyll and captures feelings of lost love.

Note to the wowsers; The female is a character, written by a writer, produced by a producer, directed by a director, acted by an actor.
If the part played by her offends you check your own moral compass. The role of Seo Ji Woo is quite despicable but his actions are not questioned. Sexism is alive and kicking - mostly females.