arduous is the race against time as one grows old. (literally "as the sun goes down, the road remains a long one.")

The hiragana syllable ひ (hi). Its equivalent in katakana is ヒ (hi). It is the twenty-seventh syllable in the gojūon order; its position is は行い段 (ha-gyō i-dan, “row ha, section i”).

(emphatic, before an adjective, non-productive) indeed, truly

(onomatopoeia) A shriek, as when recoiling in fear or disgust.

手の平, 掌: palm (inner, concave part of hand)

昼: noon, daytime / 蛭: leech / 蒜, 葫: allium

放る:

干る, 乾る: / 嚔る: / 簸る:

火花: spark

必須: indispensable, required