Background:
This story takes place after one of Leylin Farlier's experiments with the Astral Gate.
This story takes place during the 100 year time skip in Warlock of The Magus World chapter 786. Leylin Farlier in the Magus World is still only a Rank 6 Bloodline Monarch and is in the midst of experimenting with the True Soul Splitting Technique and conceptualizing the Rank 7 spell: Alternate World Reincarnation.
During one of his experiments, he uses an incomplete Alternate World Reincarnation spell to send out a tiny piece of his true soul to gather data. The why and how of this doesn't really matter for this story.
Miraculously, the split soul that was supposed to disintegrate in the Astral Realm after data is gathered for some time somehow survives through sheer statistical improbability. Through luck, fate, or perhaps even a mysterious guiding hand (not sure yet), it survives countless spatial storms and wormholes, finally landing in the Mushoku Tensei world.
Leylin Farlier's split soul subsequently parasitizes the soul of Luke Notos Greyrat, before completely taking over after consuming it for nourishment.
The connection between the split soul and the original Leylin Farlier was severed ages ago, thus there will be no interactions between the original and Luke Notos Greyrat.
Glossary (will be updated as the story progresses to avoid spoilers)
A.I. Chip: Leylin Farlier's 'golden finger'. His cheat code. It is an advanced and intelligent microchip that has since fused with the soul of the original Leylin Farlier. This fusion allowed Leylin to access the chip's functions on a deeper level, making all the information it analyzed and stored become a part of his own memory and abilities.
The functions of the A.I. Chip are cheat-like and invaluable to Leylin. Some of its key features include:
Data Analysis - It can analyze data on command, running simulations and making deductions based on the gathered information.
Data Storage - It can record and store everything the host experiences through their five senses, effectively creating an extensive database of information. Empirical data showed that it had enough wherewithal to store over 10,000 years' worth of events.
Language Translation - The chip can translate and comprehend languages from different cultures, helping Leylin communicate and understand texts and inscriptions in foreign tongues.
Skill Enhancement - The A.I. Chip assists Leylin in improving his cultivation techniques, refining potions, and enhancing his spellcasting abilities by providing real-time feedback and suggestions.
Power Tracking - The chip can monitor Leylin's magical power and vital signs, alerting him to potential dangers or opportunities for advancement.
World Barrier: Most worlds have a protective sphere surrounding it that resists the intrusion of foreign entities. Powerful worlds have proportionately stronger world barriers. The Six-Sided World's barrier is weak as hell, comparatively, which gives you an idea of the relative difference in power scaling between the two novels.
Astral Plane: the sea of void and cosmic energy between the worlds of the universe. Imagine it as outer space.
Spatial Storm: Storms of spatial energy and cosmic radiation that exists within the Astral Plane, can absolutely fuck up spiritual seeds sent out by Magi to probe and scout for worlds to loot and raid unless one has the exact coordinates of their destination.
Magus Rankings
Rank 1: Equivalent to Saints in Mushoku Tensei. Though arguably even Acolytes can defeat Saints who are not within immediate close combat range.
Rank 2: Equivalent to Emperors or weak God-ranks in Mushoku Tensei.
Rank 3: Stronger than modern day 'God-ranks' (Sword God, Water God, North God)
Rank 4Morning Star: Equivalent to Saint Millis at his peak.
Rank 5 Radiant Moon: Hitogami is probably at this level, not sure yet.
Rank 6 Breaking Dawn: The Original Leylin Farlier is at this level, but he is considered to be only half a step to Rank 7 as he has comprehended 99% of the Law of Gluttony.
Rank 7 and beyond: Beings who have comprehended complete Laws (Law of Fire, Space, etc). Considered godlike entities, equivalent beings will not be appearing in this novel.