As of my knowledge cutoff date in September 2021, there has been no episode of the One Piece anime that shows Luffy using Gear 5. Gear 4, also known as Boundman, is the highest level of Gear that Luffy has demonstrated in the anime. It's possible that future episodes or chapters of the One Piece manga may reveal a Gear 5, but as of now, it has not been shown in the anime. **

As of now, there has been no official announcement regarding the introduction of Gear 5 in the One Piece series. The creator of One Piece, Eiichiro Oda, has not revealed any specific details about when Gear 5 will be introduced. It is likely that Gear 5 will be revealed at a significant moment in the story, but fans will have to wait for Oda to unveil it in the manga or anime. **

Rotary engines, also known as Wankel engines, are a type of internal combustion engine that operates on a unique rotary design. Unlike traditional piston engines, rotary engines use a triangular rotor that spins within a chamber to produce power. This design allows for a smoother and more compact engine with fewer moving parts, resulting in high power output for its size. Rotary engines are known for their high-revving nature and have been used in various applications, including sports cars and aircraft. **

Rotary engines have both advantages and disadvantages. On the positive side, they are known for their high power-to-weight ratio and smooth operation. However, they also have a reputation for being less fuel efficient and more prone to high oil consumption and emissions. Additionally, they can be more difficult and expensive to maintain and repair compared to traditional piston engines. Ultimately, whether a rotary engine is "bad" depends on the specific needs and preferences of the user. **

No, the surviving twin does not die automatically when their twin dies. While the loss of a twin can be incredibly difficult and emotionally challenging for the surviving twin, it does not mean that they will die as a result. Each individual has their own unique life and health circumstances, and the death of one twin does not necessarily mean the death of the other. However, the surviving twin may experience profound grief and emotional distress following the loss of their twin. **

A rotary harrow is a farm implement used for breaking up and smoothing soil before planting. It consists of multiple sets of rotating tines or blades that work the soil, breaking up clumps and creating a fine seedbed. Rotary harrows are commonly used in agriculture to prepare the soil for planting crops such as grains, vegetables, and grass. They can be attached to tractors and come in various sizes and configurations to suit different types of soil and farming practices. **

A rotary hammer is a powerful tool used for drilling and chiseling hard materials such as concrete, stone, or masonry. It combines the functions of a hammer drill and a chisel, allowing it to both drill into tough materials and break them apart. The tool uses a piston mechanism to deliver rapid, powerful blows to the material, making it more efficient and effective than a standard drill for heavy-duty tasks. Rotary hammers are commonly used in construction, demolition, and renovation projects. **

The twin born first is typically considered the older twin. This is because the first twin to be born is usually conceived first and has spent more time developing in the womb. However, in cases of twins born via C-section, the twin who is delivered first is still considered the older twin, even if they were conceived second. **