St. Olaf has a very music-focused culture and a phenomenal orchestra (lots of videos available on YouTube), and a very robust Japanese program https://wp.stolaf.edu/japanese/ . It’s not quite as competitive an admit as the Northeast schools on your list, but it has a reputation for intellectual seriousness and rigor, and would undoubtedly be harder to get into if more people wanted to be in rural Minnesota (about 45 minutes outside of Minneapolis, in the same town as Carleton). Not as much risk of its being “too small” as some LAC’s, with around 3000 students.
URochester also has good depth in Japanese language and Asian studies, and a substantial population of Asian international students. Terrific music opportunities and high quality ensembles; students can study with Eastman faculty.
Lawrence U in Wisconsin is another music-focused school, with a lot of the social life revolving around both formal and informal performances; non-majors are welcomed in any level of conservatory ensemble that they’re qualified for. The students who hosted my daughter for lunch and an ensemble rehearsal were genuine and welcoming and clearly very warm and supportive towards one another as well. Another terrific place for a kid who tends to build relationships through the arts.
Earlham is a Quaker school like Swat and Haverford - a bit less of a pressure cooker but still rigorous, with a particularly strong Japanese program. https://earlham.edu/japanesestudies/ Music YouTube channel is here https://www.youtube.com/channel/UCTG4mKWuHjUfUutxOnrmhEQ