Polyline tool to fill based on reference lineart layer. Alternative to lasso for more precision when lines are very close together.
![](//assets.clip-studio.com/en-us/description/2151656/img/3398616224-9844-5b8e-3d8c-cfd36a0f8e.gif)
1. Set the lineart layer as reference layer.
2. Create a new layer under the lineart layer as the color layer.
3. Use tool to enclose and fill color.
![](http://assets.clip-studio.com/en-us/description/2151656/img/3398616224-9844-5b8e-3d8c-cfd36a0f8e.gif)