Japanese classification society ClassNK has granted approval in principle (AiP) for the design concept of a hydrogen-fueled engine-compatible oil tanker with an electric propulsion system. The project, developed by Uyeno Transtech, Yanmar Power Technology, and Mitsui E&S Shipbuilding, is part of the Nippon Foundation’s initiative to develop large-scale hydrogen-fueled domestic tankers and showcase zero-emission ships. This approval from ClassNK is significant as it is the first AiP granted for an oil tanker designed to use liquefied hydrogen as fuel, highlighting advancements in sustainable maritime technology. The certification process involved a comprehensive assessment of the design concept against ClassNK’s guidelines, specifically focusing on ships using alternative fuels and fuel cell power systems aboard ships. This milestone underscores the progress in eco-friendly maritime solutions and the commitment of industry stakeholders to embrace innovative energy sources for a more sustainable future.