Sydney Miyao played in the orchestra at Moanalua High School but earned elective credits participating in the after-school performing arts program at Castle High School. The contacts she made helped her achieve the almost impossible dream of staging and producing her first musical, “Petrichor,” before she leaves Hawaii next month to begin her freshman year at the University of Miami’s Frost School of Music. Miyao wrote the show’s book (script), as well as the music and lyrics of all the songs. She also composed all the additional orchestrations.

“Petrichor” was premiered as a fundraiser for the Castle Performing Arts Center in May. It closes a second three-show run with a matinee performance at 3 p.m. today at Castle High School. (For ticket information, visit ShowTix4U.com.)

Miyao, 17, will be in “the pit” playing keyboards and conducting four other musicians.

How does the word “petrichor” tie in to the story?

I wanted a title that had a relationship to rain (because) I have a lot of rain motifs through the show, like a monsoon, like something coming to an end and also beginning. My best friend suggested “Petrichor” and explained that it’s the smell of rain after a long period of dry, arid weather. It’s a feeling of euphoria, nostalgia and sadness all in one.

What got you interested in writing a musical?

My piano teacher, Jenny Taira, was talking to me about (recording) an EP as a senior project for high school. But I was starting to get into writing music as a priority in my life and I was really interested in writing a musical.

What can you share about the story?

It’s about me confronting some of my own fears and asking these questions to a larger audience — and bringing up this sort of dialogue that I haven’t really seen in media. I have a younger brother and we have communication issues, and I wanted to write a show about communication, what it means to have a sibling, what it means to have family, and what it means to not have a relationship with someone that you’ve known your entire life.

Describe the experience of seeing the characters you wrote come to life on stage.

It’s been so fun. Especially ’cause I have a live pit of student musicians, working with them and seeing the story and the music come to life, and also working with the actors who bring their own questions to the characters that make me reexamine some things that maybe I didn’t look into as much. These are things you don’t necessarily see in a story when you’re writing it out.

What have the biggest differences been for you as a writer/director after having done musical theater as a performer?

You don’t think, when you’re (performing) in a musical, about everything that goes on. Here I have my hands in every single aspect. I’m directing, I’m conducting the musicians, I’m working with the light designer and coordinating sound with the sound people. It’s been crazy, managing all these elements, but it’s been an awesome collaboration. We’re all public school students — from Moanalua, Castle and Kapolei — and we’re all 18 and younger. It shows what a learning center can provide you and what sticking to a project can do when you have the right people.

What would you like to be doing 10 years from now?

I’d like to have a musical on Broadway.