Japanese giant Mitsui OSK Lines has teamed up with a mystery investor to buy into Reliance Industries’ six VLECs.

MOL first linked up with Reliance to charter the vessels on Christmas Day 2014 while they are still under construction at Samsung Heavy Industries.

Reliance today announced MOL and its partner had acquired a “strategic stake” in what where the world’s first VLECs.

The terms and size of the investment were not disclosed in a statement to Reliance investors in Mumbai today.

MOL director Takeshi Hashimoto said the investment had added six unique vessels to the company’s fleet of over 850 ships.

“MOL has detailed knowledge about these assets having supervised the construction and delivery of the six VLECs and subsequently operating them since their delivery,” he said.

“We are therefore happy and look forward to use this strategic opportunity to be a joint owner and to significantly strengthen our existing relationship with Reliance.”

Tokyo-listed MOL may not be the only global heavyweight to co-invest with Reliance this week.

Reuters reports today the world’s largest oil producer Saudi Aramco is set to buy a stake in its refining and petrochemicals business.

Reliance is understood to have ordered the VLEC sextet at a price of around $700m in the summer of 2014.

Today the ships, the 87,300-cbm Ethane Crystal and Ethane Emerald (built 2016) and the 2017-built Ethane Opal, Ethane Pearl, Ethane Sapphire and Ethane Topaz, are priced by VesselsValue at $631.35m.