Production
Liz and the Blue Bird is the third film based on ''Sound! Euphonium, following Sound! Euphonium: The Movie – Welcome to the Kitauji High School Concert Band and Sound! Euphonium: The Movie – May the Melody Reach You!'', both of which were abridged adaptations of the anime. However, the movie takes place within the universe of the television series, in which Mizore and Nozomi appear as supporting characters; conversely, main characters in the series such as Kumiko and Reina only appear in supporting roles.[2] Despite being a spin-off, the film is also meant to work as an independent story, and does not require knowledge of ''Sound! Euphonium''.[2][3][4] Character designer Futoshi Nishiya re-designed the characters instead of using the designs from the series, in order to better fit the film's style, story and themes.[2][3][4][5] The crew also included Mutsuo Shinohara as art director, and Naomi Ishida as color stylist. Stephanie Sheh served as casting director and ADR director for the film's English release.[5][6]
Yamada originally discovered the characters of Mizore and Nozomi when they were introduced in the second of Takeda's novels, ''Sound! Euphonium 2: The Hottest Summer of Kitauji High School's Wind Ensemble Club''. She stated: "I was moved by the focus [Takeda] placed on developing new characters in that section of the story, and remember becoming captivated with the relationship of Mizore and Nozomi. At the same time, I thought it was a terribly sinful story. And yet so very transparent and rash... At any rate, I thought it was fascinating. I can definitively not come up with this kind of perspective by myself. Since I liked it so much, the two have since been on my mind." Yamada had worked as storyboard artist and occasional director for the anime series; at the time, Takeda was working on a two-part sequel to the ''Sound! Euphonium novels that would be published as two different novels (Hibike! Yūfoniamu Kitauji Kōkō Suisōgaku-bu, Haran no Dainigakushō): the first, Zenpen, would be focused on Kumiko, and the second one, Kōhen'', on Mizore and her relationship with Nozomi. The series' crew read the novels before they were published in order to prepare a potential film adaptation; as it would have been difficult to properly depict both Mizore and Kumiko's stories within the same film, the team decided to make two different films instead, with Yamada directing Mizore and Nozomi's because of her "increasing interest in them", and Tatsuya Ishihara, the main director of the series, directing Zenpen, which would be titled Sound! Euphonium: The Movie – Our Promise: A Brand New Day and would be released the following year.[4]
Yamada stated about the making of the film: "My first thought was to put my impression of Nozomi and Mizore's story into something visual. Then, when pulling myself right up-close to the problems and growth the two girls experience, I made sure to catch any small changes or realisations the two may have. I wanted this film to be in its most suitable form to match what this story wanted to depict. [...] I wanted to catch and depict these softer, more subtle aspects. For example, even the slightest aversion of their eyes is something born from their thoughts and feelings. This is something I wanted to take great care of – I wanted to make sure I didn't lose any of it. It's like watching and quietly holding your breath, recording what you see. Like watching the girls behind a pane of glass; a single touch enough to make them disappear. I put importance in using colour to reflect this sense of fragility and fleetingness. [...] For this piece of work subtle emotions and the buildup of feeling was important. So I was careful as to not add acting that was formulaic, like 'they're sad so they'll make a sad face'. For example, the flautist Nozomi. When she lifts the corners of her mouth and narrows her eyes, it is recognised by the other that she is smiling. She's the sort of girl who thinks like this, but looking at it the other way, by ‘smiling’ she's maintaining the distance between her and the other. It was important to not take shortcuts in depiction, as to protect the dignity of these girls who live their lives thinking about this with every step they take."[3]
Nozomi's voice actress Nao Tōyama stated that Yamada told her that "Mizore's feelings towards Nozomi and Nozomi's feelings towards Mizore aren’t the same. Both care about each other, but their feelings grow apart. They feel empathy for each other, but their relationship is special and unusual."[2] Yamada also stated in another interview that she "had a very hard time depicting the intricacies of the relation between Mizore and Nozomi. It seemed like one would get a completely different impression by just the way they ended their words in every bit of their conversations. I absolutely wanted to be faithful to the feelings of the two. It was a very risky speech style we went for, however we did not intend to make something where the people we show it to simple-mindedly sees them as "very good friends". In order to protect dignity, so that there was not any falsehood (in the drawings), I was constantly careful not to make it showy."[4]
Tōyama stated "Nozomi was depicted in the TV series as a truly nice, cheerful person loved by everyone. I tried to render her charisma, not just her motivated and driven personality. However, in the movie, she shows her imperfections, which weren't depicted in the TV series due to her not being the main character. For instance, she can be cunning and jealous of even Mizore, who she really cares about. I think viewers of the movie will feel an affinity with her human side. To be honest, I was confused when I read the script at first. I didn't want to destroy the fans’ image of her from Sound! Euphonium, even though the movie is a completely new story. I hope viewers understand that Nozomi is the same girl from the TV series, and the movie shows different aspects of her not shown before. I'd like to portray her without destroying her image, but surprise viewers with her human side. To be honest, I felt that I could relate to Mizore more than Nozomi at first. I understood Mizore's feelings but not Nozomi's. I didn't understand her looking away or shuffling her feet at the crucial time. I thought she wasn't the girl who I knew well. It took a while for me to understand why she acted like that. She has too much on her mind and can't handle her emotions anymore. On the other hand, Mizore stays the same in the movie, so it's easy to understand her."[2]
Mizore's voice actress Atsumi Tanezaki stated: "There was no confusion about Mizore's role. How she treasures being with Nozomi hasn't changed a bit from the TV series. However, there were very few scenes of the two together in the TV series. There were only the scenes of them making up and then a few conversations. Therefore, I wondered how I could render her feelings when they were chatting and joking around or playing together in the sun. The director told me that Mizore feels like it's the last chance to be with Nozomi every time she meets her. She always feels insecure about her friendship with Nozomi and fears it'll end abruptly without warning. I understood those feelings towards her during the TV series, so I told her ‘I know. I get it.’ Mizore treasures every moment with Nozomi and was simply happy when Nozomi reacts to her joke by saying, ‘What's that?’ She hasn't changed in that respect."[2]
Both Tōyama and Tanezaki pointed at the importance of Mizore always walking behind Nozomi rather than next to her. Tōyama stated: "Viewers see them from the lateral view, however, from Mizore's perspective, she is always watching Nozomi's back. When Mizore becomes an adult and looks back on her teenage years, she probably remembers Nozomi's back. I become emotional just thinking about that."[2]
In an interview with Anime News Network, Yamada stated in response to the question of if she'd describe Liz and the Blue Bird as a "gay love story": "On Liz and the Blue Bird, as well as Tamako Love Story, a lot of people read into that as a gay love story, as you have mentioned. But that wasn't so much the intention. Just to explain a bit more, it wasn't so much the representation of one sexual orientation, but it was a representation of adolescence, what the characters tend to go through at that time. During those years of our lives, everything seems intensified, whether it be friendships, or the reliance on a certain person, or the dependency…. Because of the limitations of the worlds that the characters live in as well. I just wanted to describe how complex living your teenage years could be, and what they tend to go through. So it wasn't a simple depiction of, "Yes, they're gay and this is their love story," because I can't comment on what kind of person they would fall in love with in the future, or who they will become. It's a portrayal of what they were at the time. The answer is, it is quite complicated."[7]
Music
Liz and the Blue Bird had two composers: Kensuke Ushio, who had scored Yamada's previous film A Silent Voice, composed the minimal-styled background music for the scenes in high school, while the background music for the Liz and the Blue Bird fairy tale segments and the concert pieces performed by the characters' wind band were composed and conducted by Akito Matsuda, the composer of the ''Sound! Euphonium'' anime series. The soundtrack was composed beforehand, and the keyframe animation done afterwards to match with it; the scenes featuring Ushio's music were particularly hard to animate, as he included the sounds of the characters' footsteps as part of the music, and their movements had to be perfectly synchronized with the sounds; the goal was to have "visuals, music, and the sounds of footsteps in complete tandem".[3][8][9][10][11]