Bouncy J-pop energy with alien invasion vibes. G.I.B. Girls in Black is a 2014 PC visual novel that's basically Men in Black but with anime girls, and the soundtrack commits to that premise hard. "wonderful!wonderful!" is an absolute earworm of an opener, and "アース・アタック" (Earth Attack) goes full sci-fi action mode.
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"女の子はエイリアン" (Girls Are Aliens) has this playful tension that sums up the whole game's tone. There's a nice mix of upbeat school life tracks and genuinely tense sci-fi moments. The instrumental versions of the vocal tracks are solid for background listening too.
If you want a VN soundtrack that's equal parts cute and weird, this one nails the balance.