Hiruko uses the Storm Release Kekkei Genkai he acquired through his Chimera Technique to produce a massive thunder cloud that can infinitely absorb chakra.
Trivia
- After Hiruko uses this technique, and the focus changes back to him from Shikamaru, his last seal changes from Tiger to Bird. When he reactivates the technique to absorb Naruto's Great Ball Rasengan, he uses the Horse seal instead.