I forgot the name of sendai puchi, but she has the cape from harrypotter for it to blend so well
Isn't it just the standard 'ninja hiding in the wall/object/tree' thing where they put a cover the same colour as the object they are hiding against over themselves?
actually i believe its Sendai (Which if i miss my translation, means night battle.)
Sendai refers to the Sendai river. What you remember as "Night Battle!" is her signature battle cry, "Yasen!"
That Sendai puchi (Sen-chan) is just doing the ol' ninja camouflage technique, much older than the Cape of Invisibility. (Perhaps even the originator of said cape.)