Kishiryu Neptune (キシリュウネプチューン) is the Kishiryu ("knight dragon") numbered 07 in Kishiryu Sentai Ryusoulger (2019). Its base form is the mosasaurus Kishiryu MosaRex (モサレックス), the partner mecha of RyusoulGold (Canalo). Unlike the three core Kishiryu – Tyramigo, Triken and Ankylose – which merge into KishiryuOh, MosaRex stands up on its own into a single-unit robot, namely Kishiryu Neptune. It therefore functions as an auxiliary/support mecha with its own combat form. The series was adapted as Power Rangers Dino Fury (2021–2022), where the counterpart is called the Mosa Razor Zord.

The transformation works by MosaRex's large jaws taking in ("biting") the Gold Ryusoul, after which the two ammonite-shaped AmmoKnuckle fists are attached. Thanks to Ryusoul connection points across the whole body (the line's signature "Ryuso Gattai" gimmick), the mecha can be combined further in flexible ways: with DimeVolcano it forms SpinoThunder, and together with DimeVolcano and KishiryuOh it forms the large combined mecha Gigant KishiryuOh. Its notable traits are its considerable size and the many freely attachable weapon and armor parts.

The DX toy was released by Bandai (Japan) in July 2019 as "Kishiryu Series 07 – Ryuso Gattai DX Kishiryu Neptune". It is made predominantly of ABS/PVC plastic and, as is typical for this line, contains no meaningful die-cast content. In MosaRex form it is roughly 45 cm long, placing it among the larger DX mecha of the range. The package contains the MosaRex/Neptune body, one Gold Ryusoul (which folds from Soul mode into Knight mode in a single motion) and two AmmoKnuckles, plus an instruction sheet. The SpinoThunder and Gigant KishiryuOh combinations require the separately sold sets (DimeVolcano and KishiryuOh, respectively). The item described here is the Japanese Bandai DX release.