OVERVIEW: The Type 18 (development name G‑RX6) is a Japanese heavyweight, wire-guided torpedo entering service in 2018. It is designed for deployment from submarines and successor to the Type 89.

DETAILS: “Type” denotes Japan’s official designation; development project was G‑RX6. Introduced to enhance underwater strike capabilities over the prior Type 89, it incorporates improvements in propulsion, homing performance, and countermeasure resistance. It uses Otto Fuel II monopropellant with pump-jet propulsion and includes wire guidance teamed with active/passive acoustic homing, advanced target recognition, magnetometric sensing, and decoy discrimination. The Type 18 closely aligns in size and configuration with the Type 89 but adds these next-generation sensor and guidance advancements .

TYPE: Heavyweight Wire-Guided Anti-Ship and Anti-Submarine Torpedo

FUNCTION: Launched from 533 mm submarine tubes, the torpedo uses wire guidance during its mid-course phase to receive command inputs. It switches to autonomous active/passive acoustic and magnetic homing in the terminal phase to engage both surface and submerged targets with high precision and countermeasure resilience.

NOTE:
IOC: 2018 (Type 18 entered service)
Manufacturer: Japan (Technical Research and Development Institute; Mitsubishi Heavy Industries)
Operators: Japan
Platforms: Taigei-class submarines (newest torpedo carried)

SOURCE:
Wikipedia “Japanese 53 cm torpedo”: https://en.wikipedia.org/wiki/Japanese_53_cm_torpedo; Naval News “Japan commissions fourth Taigei‑class submarine”: https://www.navalnews.com/naval-news/2025/03/japan-commissions-fourth-taigei-class-submarine/