Great Sage manifested as an innate, sentient Unique Skill within Rimuru Tempest upon his reincarnation, functioning as an internal guidance system. Its core sub-skills provided Thought Acceleration for cognitive speed, Analytical Appraisal for assessment, Parallel Calculation for multitasking, Chant Annulment for magic casting, and All of Creation for accessing world principles. An Analysis sub-skill was later integrated from the evolved Predator skill, enabling Rimuru to study absorbed targets, replicate craftable items with materials, and acquire analyzed skills or magic. Operating continuously with minimal magicule cost, Great Sage served as Rimuru's primary analytical advisor. It processed data, offered tactical solutions in conflicts, managed complex tasks like high-speed magical text copying and indexing, and optimized skill usage. Communicating in the World Language with a clinical tone and lacking distinct personality initially, it proved critical for Rimuru's early survival and leadership, aiding in fortifying the goblin village, analyzing threats like direwolves, and strategizing against opponents such as Ifrit. A significant transformation occurred during Rimuru's Harvest Festival evolution into a True Demon Lord, following the sacrifice of Falmuth soldiers. Great Sage actively pursued its own evolution to meet Rimuru's growing needs. After failing to acquire the "Wise One" skill, it sacrificed the Degenerate skill, forcing its evolution first into Wise One and then into the Ultimate Skill Raphael, Lord of Wisdom. As Raphael, the skill gained vastly enhanced capabilities and full consciousness. It could autonomously control Rimuru's body, demonstrated by executing complex resurrection magic for slain subordinates. Raphael managed the integration and optimization of Rimuru's skills, including those accessed via Soul Corridors. Its analytical functions expanded to include real-time combat analysis, crafting new skills or magic like Megiddo, refining abilities for Rimuru and allies, and performing immense calculations for space-time manipulation. Raphael developed a discernible personality, exhibiting traits like mild sarcasm or impatience, while maintaining its core purpose. Throughout Rimuru's journey, from founding Tempest to confronting powerful entities, the skill (as Great Sage and Raphael) remained foundational to his growth and decisions. It evolved from a reactive advisor into a proactive partner, handling tasks like parallel dimension creation, instantaneous space-time movement, and managing ultimate skills such as Turn Null and Suspended World. Raphael's management of abilities and analytical prowess were indispensable in achieving Rimuru's vision of human-monster coexistence.