"Terrifying Secret" (恐るべき秘密, Osorubeki Himitsu) is episode 85 of the Naruto: Shippūden anime.
Kakashi, Chōji, Ino and Shikamaru survive Kakuzu's attack, with Chōji wondering how Kakuzu survived being struck in the heart by Kakashi's Lightning Cutter. Shikamaru correctly deduces that Kakuzu has five hearts - one in his body and the others in his four masks, one of them which was killed by Kakashi. Realising that the only way to defeat the duo is to split them up, Shikamaru offers to take Hidan away while leaving Chōji and Kakashi to deal with Kakuzu. Using his Shadow Sewing Technique along with his Shadow Shuriken Technique to try and trap Hidan, Shikamaru resorts to rushing at him face to face to link their shadows using his Shadow Imitation Technique after punching him. Now in control of Hidan's body, Shikamaru has him drop his Triple-Bladed Scythe on the ground and runs away into the forest, with Hidan being forced to follow him.
Meanwhile, Kakuzu merges two of his masks into one in order to combine their Fire Release and their Wind Release. Kakashi realises that each mask possesses a natural chakra affinity that Kakuzu has access to. Kakuzu decides to take their hearts in order to replace the one Kakashi destroyed and attempts to kill Kakashi. In the forest, Shikamaru sets up various traps using kunai and explosive tags, but is unable to maintain the Shadow–Neck Binding Technique on Hidan. Free to move once again, Hidan unveils his Retractable Spear and seemingly cuts Shikamaru's cheek with it. Ingesting the blood, Hidan draws a Jashin circle and stabs himself in the heart.
|Role||Seiyū||English Voice Actor|
|Shikamaru Nara||Shotaro Morikubo||森久保 祥太郎||Morikubo Shōtarō||Tom Gibis|
|Ino Yamanaka||Ryoka Yuzuki||柚木 涼香||Yuzuki Ryōka||Colleen O'Shaughnessey|
|Chōji Akimichi||Kentaro Ito||伊藤 健太郎||Itō Kentarō||Robbie Rist|
|Kakashi Hatake||Kazuhiko Inoue||井上 和彦||Inoue Kazuhiko||Dave Wittenberg|
|Hidan||Masaki Terasoma||てらそま まさき||Terasoma Masaki||Chris Edgerly|
|Kakuzu||Takaya Hashi||土師 孝也||Hashi Takaya||Fred Tatasciore|