There was something happening.
The Anbu Fox perched on a heavy branch of a cypress tree, gloved fingers inspecting the layered bark. There was a mark in it-- deep, sending cracks and fissures all throughout the sturdy wood, and seemed to have been left at an angle; like the weight of the impact had rolled front-to-back across the branch. The mark was unquestionably a footprint, the remains of some chakra-infused run along the canopy of the forest. A shinobi had been that way, in enough of a hurry to choose speed over caution. Or unaware of the patrols through this part of the forest, but his instincts turned that aside as unlikely. Konoha shinobi would have known he was here, and if there was enough urgency to warrant this kind of behavior ANBU would have been informed regardless. The messenger might even have come to him themselves, or at least inform him of their presence.
A foreigner would do neither.
For almost three years, Satoshi Matsumodo had patrolled this section of Fire Country. It was an old part of an ancient forest, full of huge trees and sparsely scattered villages. This was the area south-east of Konoha, between Otafuku Gai and the coast-border with Wave Country. Almost a hundred square miles in size, it was vast, and yet only one of nine trouble spots identified by the Hokage. Each, he had ordered, would have a single ANBU agent patrolling at all times, in varying rotations. It would not replace the genin and chuunin squads who patrolled, but having a high class shinobi within a few hours run was a fail safe, to prevent the invasions of criminals and enemy shinobi that seemed to constantly test the borders.
This was his second week in a three month patrol cycle, and Satoshi had been edgy the whole time. Something ate at his senses, a subtle and yet constant itch in the back of his mind. It had led him to longer patrols, combing the more unsavory routes used by criminals and-more worryingly- missing nin. But the mark on the branch was the first thing he'd found, leading him to-
The chakra signals hit him like waves on a shore, driving the Anbu's attention away from the tree and back to his surrondings. A shinobi, strong, probably jounin or ANBU, was nearby. Nearby and almost surely dead. There was a sense of finality to the wave, and-marking the spot of the mark for further study-, Satoshi leapt into motion. It was close to the village at the major crossroads in this territory, but the fading awareness led him past it. Past the outbuildings and the fields, until he was lead in front of an abandoned, ramshackle cabin.
A rapid inspection found the body, the markings of a mist shinobi. Touching nothing, the masked warrior backed from the structure, then-with a flurry of hand signs- blew a thin stream of white hot flames against the ancient wood. It lit instantly, a bright and sudden light among the darkness of the night. Designed to attract attention, Satoshi could only hope that the killer would be suspicious and at least return to investigate.
Drawing the black hood of his cloak over dark brown hair, the Anbu Fox faded back into the trees, resuming his patrol-- and waiting.