This song is a rite of passage for Vietnamese students. Here is a blog post capturing the bittersweet nostalgia of that era. If you were a 90s kid (or early 2000s) growing up in Vietnam, there is a specific sound that triggers instant nostalgia. It isn't a Vietnamese pop song. It is the opening riff of a Japanese song by a duo called Yuzu.
We realized that "Mùa hè cuối cùng" (The last summer) isn't actually a date on the calendar. It is the moment you realize your friends are becoming strangers, your childhood home feels smaller, and the carefree days are gone. Bai hoc Natsuiro- Mua he cuoi cung Tai xuong mi...
It looks like you are referencing the song (夏色) by the Japanese band Yuzu , specifically the famous Vietnamese version titled "Bài học Natsuiro – Mùa hè cuối cùng tại xuồng máy..." (or the iconic line "Mùa hè cuối cùng, ngồi trên xuồng máy..." ). This song is a rite of passage for Vietnamese students
It was slow. It was sad. It was the soundtrack to every graduation ceremony you never wanted to attend. It isn't a Vietnamese pop song
But we didn't know Yuzu back then. We knew the ringtone. We knew the lyric: "Mùa hè cuối cùng, ngồi trên xuồng máy, đi tìm lại những kỷ niệm xưa..."