This book provides essential information about high-pressure metamorphosed peridotites, central Japan. Three essential topics have been discussed from Chapter 2 to Chapter 4 in this book. Chapter 2 deals with the peculiar peridotite, enriched with Ti-rich chromian spinel, and its genesis to deepen our understanding of the forearc upper mantle materials and processes above the subducting slab. Chapter 3 reports trace and REE chemistry of peculiar hydrous peridotites with Ti-rich chromian spinel to unravel their petrogenesis and to provide important information about the enrichment processes...