一心いっしん不乱ふらん
isshin furan

Noun
na-Adjective

1. wholeheartedly; with heart and soul; intently; with undivided attention; with intense concentration; single-mindedly

Yojijukugo
自分じぶん仕事しごと一心いっしん不乱ふらんみなさい。
jibunno shigotoni isshin furanni uchikominasai.
Give yourself to your work with body and soul.