Complex sentence: The Build Strike Gundam Cosmos is an improved version of the Star Build Strike Gundam, used by Sei as defending champion in the Japan 3rd Block tournament of the 8th Gunpla Battle World Championships.
Split into simpler sentences: The Build Strike Gundam Cosmos is an improved version of the Star Build Strike Gundam. It is used by Sei as defending champion in the Japan 3rd Block tournament of the 8th Gunpla Battle World Championships.