Why do the South Koreans despise Japan up until now?

Earlier this year, Maison Kitsune (Paris based with a French and Japanese owned clothing brand) got social media threats by South Koreans in the use of the Japanese military flag with using a South Korean native as their model. The Rising Sun flag which featured on their Pre-Fall 2016 Men’s Collection has brought up some controversy toward South Koreans.

(credits: Maison Kitsune Fall 2016 Men’s Collection Lookbook)

To most of South Koreans, The Rising Sun flag is offending as well as means aggressions and imperialism due to the actions of Japan during the World War II.

The Japanese invasions of Korea began in 1592 until 1598. Although the invasion was in the 1500s, Korea was already under Japanese rule since the end of the Jeoseon dynasty in 1910 until 1945.

As a comparison, Japan also took over Indonesia in 1942 until 1945. Indonesians were happy embracing and welcoming the Japanese in the hope of freedom from the Dutch colonialism (The Dutch took over Indonesia in 1800 until 1942, but being freed from any influence in 1949). However, the promised freedom was a lie, instead they forced Indonesians to do inhumane works for the benefit of the Japanese, to be a Romusha. A Japanese word for denote forced laborers.

The Romusha (credits: http://goo.gl/vfbp7B)

The romusha were paid daily after they finished their labor just enough for the day so they have to work again on the next day to continue living.

The Japanese did doctrine gradually that Japan was “The Light of Asia” as they were the only Asian nation that had successfully revolutionized into a modern society and remained independent when most Asian countries had been under European or American power.

What happened to Japanese invasions of Indonesia was similar to Korea.
During the Japanese invasions of Korea, they said it was one of the reasons for Korea separations into North and South, although they were already holding different principle just like in China. Except for China, they united when the Japanese invaded.
Choosing alliance might be one of the reasons why they were separated as they already held different principle in the first place.
The North with Russia and the South with America.

The Groundbreaking Ceremony During the Japanese Invasion in Busan (credits: https://goo.gl/6OGOxf)

However, why are the Indonesians not spreading hate campaign towards the Japanese like the South Koreans?
Is it the forgiveness culture or the gradual doctrine by the Japanese?
Furthermore, why do up until now the South Koreans hate Japan in comparison with Indonesians?

History meant to be learned.
Indonesians do not forget about the invasions either by the Dutch or Japanese, but it is just no use to hate them now.
By spreading and keeping hate, it will not make the country better, it will not make us better.

The past is in the past.
We should forgive, but not forget and focusing on how to develop to make our country better.
Better we do something to improve ourselves to contribute to the country you live in.
Better we be loving.

We need not destroy the past. It is gone.” — John Cage on “Lecture on Nothing” (1949)