How to remove the impeller screw
洗濯機用パルセータ-用ネジ [PF-3150 JCF]
The screw is right-handed, so undo it with counterclockwise rotation.
You will need a PH3 screw driver head and maybe small spanner to help remove the tight screw.
Removing the plastic cap will be difficult but you will need a flat head screw driver to pop it out.