How about alllllll the academy students gather round the base of mount Hokage-moore as tsunade tells stories from the old days of Konoha (Back when the nin were trianed for fighting wars not little missions). All it would need is a nice Waynes world flashback and bam.. filler.in between each the kids could be like.. "Oooh ,Tsunade-sama, onegai,.. tell us another stowwwyy" and then it would somehow ease into the kakashi gaiden.