In a recente interview in Barcelona Mashima detto these two things:

- When asked why he gave his protagonists the names of each season(Natsu,Haru) he responded that he wanted non-Japanese readers to learn some words in Japanese.

- When asked about the possibility of Natsu and Lucy ending up together, Mashima responded da revealing the name of their child; Nashi

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1. Nashi: Takes the Na in Natsu and the Shi in the Japanese way of Scrivere Lucy’s name which is Rushi
2. Nashi means:
- IIsn’t here yet”
3. It’s a feminine name


Source: link

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Oh yeah I'm so happy for this! ^^
Can't wait to find out how Nashi looks...she must be really cute! ♥