If someone hasn't already done this, and you guys are not fluent in musical language, then that's fine because I'm going to explain as best as I can and in my words how Harumi's musical motif in Ninjago can help us see how she changed.
Jay Vincent and Michael Kramer were the composers for Ninjago's soundtrack, and created Harumi's motif. In the soundtrack, they associated wind instruments with the good guys, and string instruments with the bad guys. When we are first introduced to Harumi in Sons of Garmadon, her motif is played by a flute --- a wind instrument. As the season progresses, we hear some minor shifts in Harumi's motif, including a stray from the sweet, light-hearted melody we got as our first impression of her to a darker, twisted undertone as we are gradually being revealed her true colors. Once we see Lloyd being betrayed by Harumi at the Oni Temple, Harumi's motif dramatically transitions from being played by the flute to the piano and the violin --- string instruments.
We are going to focus, however, on how Harumi's motif was being played in Crystallized, specifically in the last episode of the season, when Harumi, Lloyd, and Garmadon get off the Golden Ultra Dragon to reunite with the ninja after the final battle was over. We are hearing Harumi's motif again, but this time with the flute once more. When Jay, Cole, Kai, and Zane give her suspicious looks, you can hear a tone of regret and sadness denoted by a minor key. The ninja's looks reminded Harumi of her evil actions, causing her to feel remorse and a want to change, which is translated in the music. However, with the ninja looking at her like that, she was probably thinking it would be impossible for a real redemption to come about her despite what she wants. Fortunately, once Lloyd says, "Don't worry, she's with us," there is literally a major shift in the tone of her motif. There is relief and joy denoted by just a split second of a note in a major key. Harumi is now a soul touched by forgiveness and redemption; through Lloyd's reassuring words she is no longer burdened by her past and can start a new life on the good side.
But it doesn't stop there. The positive ending of her motif blends in with the rest of the music following that conversation, creating a building and a swell of hope --- note the word building --- and acceptance. After the Golden Ultra Dragon disappears, Master Wu appeals everyone to rebuild, and that is exactly what they did towards the end of the episode with the Monastery. Guess who also joined in the rebuilding of the Monastery? Harumi.
Harumi's redemption may not be as well written as it should be (that is a conversation for another time), but the music does a better job of telling her story of change from a person torn by unresolved pain and seeking revenge to a person redeemed and (hopefully) accepted back into society after realizing that what she did was wrong. Jay and Michael are excellent composers, and their music makes me appreciate Harumi's complex character even more.
