heartstrings; deepest emotions
Figurative use, often in the phrase 琴線に触れる (to touch one's heartstrings). Refers to something that deeply moves or resonates with a person.
His performance touched the heartstrings of the listeners.
The final scene of that movie will probably touch many people's heartstrings.
koto string
Original literal meaning: the string of a koto (Japanese zither). Now rare outside historical or musical contexts.
See also: 琴 (こと)
琴線 originally referred to the strings of a koto.
heartstrings; innermost soul
Compound of 琴 (koto, a Japanese zither) and 線 (string, line). The figurative sense 'heartstrings' developed from the idea of strings that resonate when plucked.