Ryusuke Sekino was reportedly born at just 24 weeks via an emergency C-section. Mom Toshiko Sekino was apparently experiencing hypertension.
Toshiko told reporters she was very worried for her child and cried a lot. Ryusuke weighed just 9 ounces when he was born, and Toshiko said he was fragile and had transparent skin.
A doctor at the hospital said Ryusuke's "blood vessels were too thin to administer intravenous drips" immediately after he was born, according to a Japanese news service.
But five months later, Toshiko now has a healthy baby boy. Ryusuke now weighs a whopping 7.4 pounds.
"I can really feel his weight now. He used to be so light," Toshiko said on Fuji TV.
Toshiko said she can now breastfeed him and is looking forward to giving him a bath at home. Japanese TV showed Toshiko on Friday holding her bundle of joy.