Moon Jun Young-The 22-year-old neighbor of Louise who wanted a younger sister. He is the leader of a the KPop boy group named ZE:A (Children of Empire). He has a weak heart and needs someone to talk to. He is a girl's perfect oppa. 

Louise Ji Sun Choi Chua-Jun Young's 13-year-old neighbor who is from the Philippines. She is half Filipina-Half Chinese and Half Korean. She hates the way her family treats her, making her like a slave in the house. She has two other sisters, Rhyn and Jenny. She became a KPop artist with her group, 81EIGHTY-ONE, 2NE1's subgroup, by the help of Yong Hwa. 

Moon Geun Young-Louise's new name given by Jun Young. She lives her new life to be with her brother who has a weak heart. When she was still Louise, her sister, Jenny was born with a hole in her heart. She understands why Jun Young wanted a sister. 

Jung Hee Chul-Jun Young's friend and the brother of Hee Young. He is a very punctuated and wild person and is also known as ZE:A's Mr. Grumpy. Although he is grumpy at times, he is a loving, caring and kind brother to Hee Young. He has a cousin named Jung So Min, who is Hyun Joong's girlfriend.

Kim Ji Yeop-One of ZE:A's members and is Kim Ji Hyun & Kim Ji Oh's brother. He likes to play computer games and is a computer whiz like his sister, Ji Hyun. He was raised in Australia by his mother, Yeon Ae. Together with his mother and sister, he comes back to Korea to study. When things start getting unreasonable, he starts speaking English, which annoys Hee Chul and Ji Oh a lot. His older brother, Ji Oh is married and has two children, Young Min and Young Soon.

Kim Tae Heon-One of ZE:A's members who lives with his older sister, Kim Tae Hee. Both his parents had passed away due to cancer when he was younger. He always talks to Hee Chul while sleeping and is the motherly member of the group.

Hwang Kwang Hee-One of ZE:A's members who is very curious. He likes to find out how things works. He is well-known for being a popular star in the variety show scene. He is the only member who had gotten a plastic surgery. He has a 4-year-old sister name Hwang Yoon Jeong. He likes to stalk Siwan's cyworld, which makes Siwan very mad.

Ha Min Woo-One of ZE:A's members who is a former JYP trainee. He is very shy like his sister Ha Min Joo, who loves to sing. He is a charismatic guy but he is also a loving brother. He is Jun Young's best friend.

Im Woong Jae-Also known in ZE:A as Im Siwan, Woong Jae is a kind-hearted person. His sister, Im Seung Hye is one who cheers unhappy people up. Both of them are alone in their house, since their parents are on business trips most the time. He and Seung Hye are very good housekeepers. He was once asked by Ji Yeop's brother, Ji Oh to do a general cleaning for their house. (He was paid for it....)

Park Hyung Sik-Described as ZE:A's tallest guy, Hyung Sik is a very cute guy with kind personality. His brother, Hyung Joon, is considered baby-faced because of his fair skin. Hyung Sik is a kind and loving brother towards his younger sister, Hyun Jung, who is 7 years old. 

Kim Dong Jun-ZE:A's member who has a resemblance to Han Ga In. He is given the nickname "scary maknae" by his fellow ZE:A members. Has a sister named Kim Eun Sun.

Kim Hyun Joong-Louise's neighbor when she came to Korea when she was just five. He knew Louise when he met her in a convenient store. He has a girlfriend and fiancee named Jung So Min, who was Hee Chul's cousin. He and Louise became close through the help of So Min and Hee Chul. But Louise has a big problem when it comes to talking to him. Hyun Joong is a 4D shillang, which means that he has his own world and tends to ignore people around him. He tries his best to brush off that trait by listening to Louise and So Min's advice to him. He is the leader of SS501, one of Louise's favorite KPop group. He is an actor like So Min.

Jung So Min-Hee Chul and Hee Young's cousin, Hyun Joong's girlfriend and Louise's neighbor. She is a pretty girl with a smile on her face. She likes Louise a lot. She is the loving girlfriend of Hyun Joong. She is an actress just like Hyun Joong. She and Hyun Joong are engaged. 

2NE1-They are the favorite KPop girl group of Louise. In fact, they are her neighbors! CL, 2NE1's leader, became Louise's friend. They make Louise happy.

Jung Il Woo-The student body of Young Ji Academy and So Min's brother. He is known for being a trouble maker and a playboy. A change happens in his life after meeting Louise. After seeing her being bullied by girls from Section 2-D, he comes to her rescue and vows to keep her safe. 

Jung Yong Hwa-Il Woo and So Min's elder brother. He is the best friend of Hyun Joong. He had introduced Louise to the KPop industry and had her debut with 2NE1's subgroup, 81EIGHTY-ONE. 

Lee Seung Hyo-Louise's favorite cousin. He is a very caring cousin to Louise. He lost his parents when he was 9 and stays with Louise's family. Whenever his ajushii and ajumoni are away, he takes care of Louise, Rhyn and Jenny.