Flushback evolves into Vacuumory when fused with a Mem-o-Vac.
Flusback is a bipedal turtle-like yo-kai with teal skin and long white eyebrows, he wears a white shirt, brown pants and black sandals, he has a puffy yellow tail and instead of a shell he carries a plunger on his back.
Flushbackmakes anyone he possesses recall memories. In the anime, he can specifically bring up bad ones.
Flushback appears in the Seaside Cave (San Fantastico).
In the Anime
Flushback first appeared in EP090 where he started out as an ordinary turtle who was traumatized from an incident where he was almost flushed down the toilet only to be saved by his owner, a little girl, using a plunger. As such when he becomes Flushback, he makes people he inspirits remember their past traumas. He first appeared where he inspirits Nate when he tries to do his class duties to impress Katie. In a bid to "forget" his past trauma, he summons Dummkap who manages to make Flushback forget his own past trauma. Unfortunately, this made both Nate and Flushback embarrassing idiots as a result and costing Nate a chance to be partners with Katie on a project.
Omoidasuppon might be based on the suppon no yuurei (ghost of the soft-shelled turtle), a youkai that once haunted a man who regularly feasted on soft-shelled turtle meat, which was once believed to have curative properties, and cursed him with uncontrollable shivers. Just like a turtle doesn't let go once it bites into its prey, this creature is very persistent in its haunting.
"Omoidasuppon" is a portmanteau of omoidasu (to remember/recall) and suppon (soft-shelled turtle).
"Flushback" is a portmanteau of flush, flashback, and leather-back turtle, a soft-shelled turtle.
"Desolvidador" is corruption of desolvidar (unforget) to make it sound like desatascador (plunger).
"Yvantouse" is a portmanteau of "Yvan" (a french name) and "ventouse" (plunger).