Kasthuri is a Tamil TV show that airs on weekdays. This story is all about a girl called Kasthuri who live in a small village and is married to someone in the city. He is called Ram. Ram is very picky and particular about everything, and he always wanted a girl who was well-educated, modern and broad minded. One day, Ram and his parents visit the village to see the girl. They wanted to see Kasthuri and discuss the matters related to the wedding of Ram and Kasthuri. After going to the village, Ram sees a girl who was very fair and beautiful. He thought that she was Kasthuri. He was very happy to see her and he fell head over heels in love with her. It was love at first sight. He accepted the wedding, and was very excited for it.
He could not wait for the day he would get married to her. He told her parents that he was ready for the wedding. Kasthuri was very happy that her marriage proposal was accepted. All the arrangements for the wedding were made, and finally it is the day of the wedding. Ram was very excited for this day, but here comes the twist. As he saw a girl who was very dark coloured as the bride, he was in shock. He realized that she is the real Kasthuri. He was very helpless. He could not stop the wedding at that time so he had no other option but to marry her. After getting married, he took Kasthuri to his hometown. After a few days, he finds the fair girl that he saw in the village when he went to see Kasthuri. He gets in touch with her and becomes friends with her.
He introduces himself single. They become very close. He does not tell her about Kasthuri. Even Kasthuri does not know about the girl. She faces many problems when she is alone. When Ram is not there, she used to face a lot of problems, and this serial is about how she solves all those problems. Ram marries the fair girl without telling Kasthuri. When Kasthuri and her father came to know about this, they wanted to break the marriage. Ram has a friend who has very good ethics and values. He knows the values of a relation, and he could not see the marriage falling apart. He took this as a responsibility to make sure that they stay together forever. He wanted to make Ram the see the inner beauty of Kasthuri. He tries to make Kasthuri and her father forgive and accept Ram.