This book contains new research essays of linguistic interface studies in or related to East Asian languages. Written by 14 colleagues or former students of Yoshihisa Kitagawa, it is also a book paying tribute to his decades of scholarships on linguistic interface studies. The chapters therein range from interface studies in syntax and other linguistic areas such as morphology, phonology, semantics, pragmatics, language acquisition, language evolution, and language faculty science. The languages under discussion are mainly East Asian languages such as Chinese, Japanese, and Korean, but also include Jordanian Arabic and Spanish, under comparative studies with respect to East Asian languages. The book appeals to both seasoned and novice researchers in linguistics, East Asian languages, and modern languages. Chapters “Impersonal Bei Sentences in Early Mandarin: Form and Function”, “Focus Inside: Evidence from Spanish and Chinese”, and “Recursive Focus Prosody” are available open access under a Creative Commons Attribution 4.0 International License via link.springer.com