It might simply be a brief description or identification of a real person, possibly for an official document or introduction.

This DVD is part of the "Junior Idol" genre. It features Rara Kudou in various settings typical of the Eic-Books production style, focusing on her performance at that specific age range. The title "Masegaki" generally implies a "cheeky" or "precocious" theme, which is a common character trope in this genre.

These are Japanese slang terms. "Masegaki" (ませがき) roughly translates to "precocious brat," a common archetype in certain subgenres, while "Tan" is a diminutive honorific used to imply cuteness or a "younger" persona.