Krar Jnr is a pet unlocked on Mazcab. He is the pet version of one of Beastmaster Durzag's beasts, Krar. He can rarely spawn in the Nemi Forest, accompanied with a message of "You hear a howling in the distance!", which is displayed for all players in the forest when he spawns. The wild Krar Jnr appears as a yellow dot on the minimap. The first player to find and interact with him in the forest will claim him as a pet. Players cannot interact with Krar Jnr if they have previously done so and unlocked him as a pet. More than one Krar Jnr can spawn in the same instance while another spawn is still active.
The best way to find Krar Jnr is to just wait in Nemi Forest until it spawns. Players should bring something to do while waiting such as Alching, training Fletching, disassembling items, etc. If the last person leaves the forest while Krar Jnr is present, the forest will change, and Krar Jnr will disappear. Krar Jnr can "spawn" but not actually appear due to an NPC limit within the forest, so one should make sure that there is little to no NPC's in the forest before trying to find the pet.
Mod Deg has stated that, on average, each world might see one spawn a week, possibly less. Also creating new spawns by entering and leaving the forest does not affect the spawnrate.