一線 (いっせん) — front line, line, boundary

一いっ線せん front line

Frequency #8018 Frequency rank among common Japanese words. Lower number = more common. Grade 2 Japanese school grade level in which this kanji is taught. Grade 1 is first year of elementary school. 2 characters 混合 mixed Mixed compound — combines different reading types in a pattern that doesn't fit the standard categories. noun Part of speech (JMdict: n)

issen

Pitch高低アクセント — Tokyo-dialect pitch accent. The number is the drop position: 0 = heiban (no drop), 1 = atamadaka (drops after 1st mora), N = drops after Nth mora. The line above each mora marks high pitch; below, low. いっせん[0] heiban 平板

Synth audio is approximate — the diagram is the canonical reference.