In episode 21, which is what the pic is referencing, Kaito is searching the ruins in Helheim for the Overlord Inves named Deemushu, when said Overlord Inves is stalking him and sic the Inves onto him. Garren being here in the pic is basically an old Blade joke of him peeking out just about everywhere (with Blade and Leangle posing as Inves). The staff thing also references Garren's actor, Amano Kousei, playing Libra Zodiarts/Principle Hayami Kouhei in Fourze.