Natsuki left the country when all the crime that his family was involved to got expose to everyone. Although he wasn't involved in anything illegal given that he has no power in their family, he was still embarrassed with all that has happened.
However, as soon as he heard the news that there was a new trial on going involving Alexander's death, he immediately went back home to check on it. And the moment he arrived was also the day that Jonas was freed from his life sentence imprisonment. Jonas looked so happy having a family reunion while he, on the other hand, was all alone now.
Clara was sent in jail and won't be going out of it for the rest of her life. And their son? He's dead several years ago. Alexander might have been mistake born from their lustful and immoral acts but he truly loved him. He loved him so much that he wanted to avenge his death.