Vocabulary
一線
いっせん
one line; (a) single line
noun
freq #7
Example sentences
彼（かれ）は愛想（あいそ）のいい奴（やつ）だが気軽（きがる）に踏み込（ふみこ）ませない一線（いっせん）を持（も）っていた。
He was an amiable fellow, but had a certain reserve that he would not let you casually trespass upon.