Abstract: A bathroom sink popup stopper assembly with an integrated strainer invisible from above the sink while in routine use that catches solids in draining water at its very first stage of downstream to effectively prevent any clogs in the drain passage and beyond. The hidden strainer, sandwiched in between the two parts of the popup stopper body and wrapping around the upper part of the popup stopper body, which is conventionally a one-piece device, that is knocked down into two parts in this invention, an upper body and a lower body that can be repeatedly engaged into and disengaged from each other to secure and release the strainer, is accessible, removable, and re-installable, without the need of any tools, from above the sink before and after cleaning or replacement with a new one if preferred or as needed.