Writing a person's name in red ink is considered disrespectful and even malicious, hoping that something bad will happen to others. Because Koreans think that writing a person's name in red pen will bring bad things to this person and even lead to his death. Moreover, in Korea, the names of the deceased are often written in red. Just like Korean tombstones, their names are often painted with red paint. Moreover, at that time, the names of prisoners who were about to be executed in South Korea were often written in red ink. Just like in Korean TV dramas or movies, when students encounter school violence, the abuser often writes some vicious words on the desk with a red pen.
At the same time, writing in red often has bad meaning. For example, when a person writes a letter or an article with a red pen, it is often her last diary or article. When writing a suicide note, a person often writes it with a red pen. In fact, it is not only South Korea, but also China. Although red is a very festive color in China, it is not good to write with a red pen in China unless the teacher corrects the homework.
Especially when writing to a friend, there is often a strong feeling that you are no longer willing to be friends with him and want to break up with him. In ancient China, when a person was going to be eliminated in a competition or a prisoner was going to be executed, his name was often crossed out in red. To sum up, when writing notes or cards in Korea, it is not allowed to use red pens, because it is disrespectful to the other party and indicates a bad meaning, so friends must pay attention to using red pens carefully.