Shrapnel and stone chips sent flying from the grenade hit the back of Kiba's protective vest. Knowing that the attacker would quickly follow-up on his first strike meant Kiba had no time to plan. After giving a quick signal to Akamaru he helped Karui to her feet, and began running the opposite direction from the large canine. As they ran the boulders behind them were all hit by explosions that left little more than craters in their wake.
"Let's split up." Karui suggested as they ran. "Spread out his attention and it'll keep us from both being hit at once, then surround him and hit his blind spot."
Upon nodding his approval to her plan Karui's deft hands formed a series of seals to gather the chakra necessary to begin scaling the vertical rock formations to their right. Choosing the opposite direction, Kiba ran into the underbrush. His hand instinctively reached for a smoke bomb, but remembering his supply shortage he thought to save it.
Inhaling deeply Kiba tried to pinpoint the assailant by his smell. The man was lucky though, as all the smoke from the explosives masked his location fairly well. The brush he was hiding in provided little concealment. Being in a bad position prompted Kiba to make the first move. If he could lure the rogue nin into the trees he could get cover against the shrapnel, it would also widen the field giving more room for Akamaru and Karui to get good flanking positions. Finally Kiba was able to smell the burning of the slow fuse his opponent must be using to light his explosives.
Moving to get a better view, Kiba saw the details that he had overlooked in the earlier rush. The shinobi was short, barely over a meter and a half. Kiba remembered being that tall when he was twelve and this man looked full grown. A mask covering the lower half of his face added to his menace. His garb was rough, but clever. A simple straw rain cloak with pine needles woven into it had a pattern that would blend well both in the trees and in a field. Doubtless he kept all of his explosives under that shroud. When he turned, Kiba took his opportunity and attacked.
"Tsuga!" Kiba shouted as he attacked, relying on the distraction to doubly aid his allies.
Kiba aimed his attack low. His attempt to cut the foe's hamstring with his Kunai failed as the man safely jumped to the side, leaving two stick grenades in his wake. From his low position, Kiba managed to bat one of the grenades back towards the short man before he rebounded and leapt into the cover of the trees.
The two explosions did not have that much force, but the blast they made dulled Kiba's enhanced hearing. Taking cover behind a tree and peeking around the edge of it, Kiba found that the rogue nin was staying in the clearing. He was standing on top of a larger boulder and rustling for something underneath his coat. Akamaru was sneaking into position in front of the rocks, on the cliff Karui gave a signal that she was ready to come down as well. When they moved in he would be forced to retreat into the trees, and Kiba would have him then. As his hearing picked back up Kiba realized that their opponent was not preparing grenades under his cloak, but making hand seals and chanting.
"Katon: shouidan jueki!"
A sound of a soft boil seemed to come from every tree surrounding Kiba. The noise grew louder and louder as Kiba felt the tree in front of him become hot. Behind him a tree not four meters away suddenly exploded, sending splinters and scalding gobs of tree sap in every direction. The shockwave knocked Kiba down. The tree Kiba was taking cover behind was the next to explode from the jutsu. Running on all fours he sought to escape from the area of effect, to no avail. He realized the had picked the wrong direction as the tree he ran towards exploded two meters in front of him. It was all he could do to shield his face from the blast as he was thrown head over heels backwards.
Karui moved after the first tree exploded, hoping that the scum she faced had to maintain concentration on his technique. By the time she was down the cliff two more explosions rocked the edge of the forest. Her eyes scanned over to Akamaru who was running full speed at the man's left side.
She drew her sword out of its scabbard on her back and prepared for a low sweeping strike, relying on the thinking that the ninken would go for a high strike when he leapt up to the rocks. As she approached from her high angle Akamaru bounded up the small hill of rocks with impressive stride.
Hands out of his coat, the rogue threw down a smoke bomb concealing the top of the hill. While Akamaru charged into the smoke, Karui held back looking for any movement within the screen. After what sounded like a struggle an explosion rocked the center of the miasma, causing the thick smoke to dissipate. Akamaru jumped back and rolled in the dirt as though to put out a small fire on his outer coat. Before deciding to rush in, Karui smiled as she noticed a scrap of cloth in the ninken's jaws.
Karui found him quickly dressing his leg while hiding between two large boulders. She pressed her chokuto against his neck, letting him know not to try anything.
"You were always a quick one Karui," he said as he slowly raised his hands out from his cloak, "glad to see you haven't changed."
Although she knew she recognized his voice, Karui was better than to let familiarity drop her guard. Rather she grabbed her hilt with both hands and opened a small slice against the neck of the man she could not yet identify.
"I didn't give you leave to speak dirt bag."
Her hand moved towards his face to lower the mask that covered the lower half of his head. Before she could she felt tugged backwards, turning her gaze slightly she noticed it was Akamaru who had bitten her skirt seeming to want to stop her. Taking another look at the man she had at sword point revealed the truth to her. No blood had come out of the nick she had made on the man's neck. With a flourish she sliced the decoy across its chest, it proved to be a log henge'd to look like the attacker. Several pieces of explosive tags fell to the ground now harmless, having been cut in half.
"Where is he Akamaru?" Karui asked, knowing full well the dog understood speech.
After sniffing the air for a moment Akamaru led them into a thicket of dead trees. Karui noted several bloodied bandages at random places, deliberately put to keep Akamaru from getting an exact location. Karui closed her eyes and relied upon her own sense of hearing. Where her teacher KillerBee was one who thrived in the noise of combat, she sought the void of silence, the peace. The rustling of the tree needles, the sound wind made as it wrapped around tree branches and trunks. She searched for the one sound that stood out, the one that did not belong.
Opening her eyes she rushed to her right and swung her sword. The slow fuse hit the ground as did two grenades whose triggers had been cut. The small man jumped back again, but he underestimated the reach of Karui's long sword. Swinging her sword overhead she cut him again. An explosion flashed as she felt her sword make contact.
Regaining focus Karui found only the straw raincoat left behind. Once again the metal of her sword was not stained with blood, which meant the rogue had gotten away again. A hissing sound came from the ground where the coat lay. She and Akamaru ran away from it, and managed to get far enough out from the blast radius to avoid serious injury. Rising from the ground where she landed, Karui helped Akamaru put out the few smoldering hairs on his tail. Smelling something awful, she then checked the back of her head feeling several burnt hairs of her own.
"Come on Akamaru, let's check on Kiba." She said trying to distract herself. Whoever this guy was, two things could be said of him. He was no amateur, and he was a dead man for messing with her hair.
Note: I'm no Japanese translator, nor do I make any claim to be perfect. But I spent a good hour looking at the Kanji, the word roots, and Japanese sentence structure before being satisfied with the technique name. The process was such, that I don't think I'll do it again.
Essentially "Katon: Shouidan jueki" should mean "Fire Release: Tree Sap Firebomb."
These occur in some cases of forest fires. The tree sap inside the trees boil and expand which causes the trunk of the tree to fracture and explode. So our mysterious assailant was boiling the trees and using them as bombs against Kiba.