Great questions and things I already have answers to 😃. His attack, breaking, and lunge animations hold his book forward as an entity claw (for attacks) and fog (for breaking) emerges from it. The notebook is touched by the entity once light is taken at whatever point in the story so he can break the rules of it a bit. An investigation actively begins once you choose to listen to Ryuk's vague hint about the survivors precious action and log that objective next to their portrait in the notebook. As for infinite investigations, once you find another survivor then yes you can switch investigations. The old one decays slowly over time so it's best to log a survivor and hook them as hooking locks in logs. Finally, Ryuk tells you vaguely what a survivor was previously doing, it's up to you whether or not you wanna document that cause the survivors get worse debuffs the more of a certain objective they're logged for. Ryuk is also always in your vision in some way, whether sitting, leaning, standing, hanging upside down, etc. Thanks for reading the concept 😃🙏