As of my last update, I couldn't find a well-known author by the name of Yasuko Yamaru. It is possible that this might be a less prominent author, a pseudonym, or a misspelling of a name. Occasionally, authors with a niche audience or those who write in languages other than English might not have widespread international recognition or readily available information about them in English. If Yasuko Yamaru is a character or an author from a specific piece of work or region, providing additional context might help in giving a more accurate description. Otherwise, I recommend checking for alternative spellings, recent publications, or specialized databases that might have more up-to-date information about this individual.