The Seo Clan is held in esteem in economic and military circles in South Korea, one such branch of the family renowned for their line of business titans. However, there is one thing the other families didn't know, the Seo were wizards and witches, who were uninterested in the bland careers the normal wizarding folk have. They have been producing business titans for several generations now and all have been as interested in business as their predecessor. Except for one. There is always a flaw in the system, no matter how much you try to avoid it.
It all started when Seo Joon-ho accompanied his father in one of their usual business meetings. He had been 17 years of age, notorious for rejecting each and every arranged marriage his father had made. He was forced to go because if he doesn't, he will be rejected of his inheritance. Kang Eun-hye was just as uninterested in marriage as he was, preferring to coop up in her room. The two were given time to know each other before they are wed in their 18th birthday.
During the year they were given to get to know each other, finding out a lot about each other. Eun-hye found out about Joon-ho's mommy problems and Joon-ho found out about Eun-hye's passion for chemical science. Are they going to fall in love? Hahahahah... no. Instead of falling in love with each other like their parents wanted, they inexplicably became platonic soulmates. Who knew you'd find your platonic other half in just a year's time? Learning of each other's predicaments, they didn't want for the other to be pulled into another forced marriage so they made a pact.
What was the pact, you ask? A platonic marriage to save each other from a possibly chaotic marriage. Being good actors they were after years of pretending to care about the families' businesses, they seamlessly fooled their parents into thinking that they were in love. Pretty soon Kang Eun-hye became known as Seo Eun-hye and Joon-ho inherited his family's company. The first test was done, the second was looming just around the corner.
Soon, their parents were asking for grandkids. Their reaction was too look at each other incredulously. They agreed to the marriage, now they have to procreate?! They couldn't find a way around this though, so they did the do and they ended up with a son, whom they called Jin-ho.
Jin-ho inherited his mother's love of chemical science and, at the tender age of 5, started to memorize the periodic table. At the age of 8, he started to join his mother in her chemical experiments. Although, he was expected by both parents to be able to inherit the business, which he greatly despises. Despite that, he complied to his parents' wishes, since he respects them greatly. His younger sister by 1 year, Eun-mi, didn't exactly feel the same. They still remained a good family behind the strict business family facade.
When Jin-ho was 10, the family moved to Britain for something he doesn't know about, but he reckons that they were moving their headquarters to Europe. No matter, he liked it here. Eun-mi, however, didn't like the move. They were fine in South Korea. Plus, she missed her friends back home. This would lead to several arguments between her and their parents. When they arrived in Britain, the family changed their names to Jun (Joon-ho), Eunice (Eun-hye), Gino (Jin-ho), and Yumi (Eun-mi).
When Gino turned 11, he was accepted into Hogwarts. The family were skeptical, because all those years and generations, they only sent their children to Mahoutokoro, and nowhere else. But their children's education was more important than tradition so they let Gino attend. He was Sorted into Ravenclaw, but he didn't really get the concept of having Houses. Like do they really need to split the student body up by traits? Whatever.
Yumi soon followed, getting sorted into Gryffindor. The siblings enjoyed the first few years in Hogwarts, studying to their very best. That is, until Gino's 4th year. Their parents wanted Yumi to pursue a career in chemical engineering, but the girl didn't want to. She wanted to pursue her own choice of career. This led into a very big argument which lead to Yumi furiously packing up a suitcase and a bag of galleons and walking out, never to be heard from again.
Gino, being the good big bro he is, became very worried about Yumi and started to look for her, to no avail. Yumi's been always good at hiding. Even his owls can't find her. Right now, he's entering his 5th year. But he's still looking for his younger sis.