younger paternal half sister

tensan silk thread; silk harvested from Japanese silk moth cocoons

菊池: a surname / 菊地: a surname

火口: tinder; a place for setting a fire

口癖: phrase that one uses regularly

wanting to put something (cigarette, food) in one's mouth

角柱: prism

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.