On Tuesday, Bangkok's Central Juvenile Court awarded Shigeta, 28, custody of 13 babies he fathered via surrogacy.
The court said it did not find evidence of human trafficking.
Shigeta's motives and rapid surrogacy raised suspicion from the New Life clinic he used to find surrogate mothers. Mariam Kukunashvili, co-founder of the international clinic, said he began pregnancies with two Thai surrogates after approaching the clinic in 2011. Then he revealed plans for more than 1,000 children, Kukunashvili told The Washington Post in an email, with as many as 20 babies born annually.
She warned Interpol in 2013 over concerns of baby trafficking, but she said she did not hear back from the agency.
The Interpol office in Thailand said it never received the messages, the Associated Press reported, and Interpol referred questions to the Thai Royal Police, which could not be reached.
Shigeta, son of billionaire businessman Yasumitsu Shigeta, said through his lawyers that he simply wanted a big family, the AP reported. He did not appear at court. The law firm that represented him there, Siam Premier International, did not return a request for comment.
Thailand banned foreign surrogacy in response to the 2014 incident and another infamous case where an Australian couple abandoned a baby born to a Thai surrogate when they discovered the baby had Down syndrome.
During the trial, Shigeta produced evidence of financial means and a plan to care for the children, including drafted bank accounts and a home near a park in Tokyo, the AP reported. A total of 17 babies were found to be fathered by Shigeta, including four sets of twins.
He also has two children via surrogates in India, CNN reported.
The mothers were paid as much as $12,500 each to carry his children, reports said.
Shigeta won custody of the other four children born via surrogacy in Thailand before this week's ruling. Those children were raised in Japan and Cambodia and were well cared for, the court said.
Shigeta fled the country after the raid in 2014, the Bangkok Post reported at the time.
Little is known about Shigeta, described by the AP as litigious in protecting his identity. After authorities revealed him as the father, his lawyers blanketed Japanese media with demands to not publish his name or names of his family members, though that proved to be unsuccessful. His father, Yasumitsu Shigeta, is the chief executive of office supply company Hikari Tsushin Inc.
Kukunashvili said her concerns were assuaged once it was revealed Shigeta came from a wealthy family. She offers her apologies, she said, but said at the same time, “we do hope that he understands that it is our professional obligation to make sure babies are in safe hands.”
There are few public photos of Mitsutoki Shigeta. One image circulated in Thai media shows Shigeta at a customs kiosk leaving the country with travel documents in one hand and a baby in the other.