Higa commented that although the theme of the movie is rather serious, the staff and cast worked hard together to make it into a film which bears hope for the future. She had also come to appreciate her mother better after working on this movie and realise how mothers have to overcome various things to raise their children so she wanted to express her gratitude to her mother. As for Suzuki, due to the difficulty of having to play an alcoholic mother with dementia, she went to get a lot of reference materials from the hospital but it was tough to digest all the information. As she won't be able to know how dementia patients feel, she had to imagine the emotions of her character and focus on the theme of loneliness when acting in this movie.
In the movie, there is a scene of the three sisters playing "Canon in D Pachelbel" on the piano which Higa revealed that the three actresses played the music personally without stand-ins. Higa and Sasaki didn't know how to play the piano at first but after intensive training starting from one month before the filming started, the three of them were able to play the piano for that scene. Sasaki revealed that at first, she thought that they would definitely be able to play the piano after the training and that they should have ample time to prepare but as the filming got closer, she started to panic and practised even harder towards the end. As for Mimura, although she knows how to play the piano, she was also concerned about the scene during the filming so she practised so many times until she could play the tune with her eyes blindfolded. Coincidentally, the three of them all come from families with three children which the director said that he didn't know that beforehand when selecting the cast.
Sources: Oricon / Nikkansports