Where does “中高型” come from?

中高型 (Japanese) comes from Japanese 中, from Japanese 中今, from Japanese 今 — now; just now; soon.

中高型 (Japanese): a pitch accent pattern in Japanese where the first mora is low pitch, then the pitch is high until the accented mora, followed by an immediate downstep with the remaining syllables having low pitch

Definitions

a pitch accent pattern in Japanese where the first mora is low pitch, then the pitch is high until the accented mora, followed by an immediate downstep with the remaining syllables having low pitch

Ancestry of “中高型”, step by step

中高型 traces back through two separate lines of ancestry.

via Japanese 中

Step	Language	Word	Meaning
1	Japanese	中	middle, medium; average; neither good nor poor;...
2	Japanese	中今	the present, as a privileged moment in eternity
3	Japanese	今	now; just now; soon

via Japanese 高

Step	Language	Word	Meaning
1	Japanese	高	maximum, the limit; high, higher
2	Middle Chinese	高	—

Every word from Japanese 今 →Every word from Japanese 中 →Every word from Japanese 中今 →