The Official Nintendo Pokémon Ranger: Paths of Light Guide Book (任天堂公式ガイドブック ポケモンレンジャー 光の軌跡) was released on March 26th, 2010 in Japan and it revealed a few hidden Ranger Signs that can not be obtained anywhere in the game. The books ISBN-13 number is 978-4-09-227144-9 and it retails for 1,260 yen.
Players must register the sign in the Ranger Sign database before it can be used. Pictures showing the strokes to draw and the corresponding Pokémon that it will summon are posted below.
A full listing of all the revealed Ranger Signs is available by clicking here.