後患 (kōkan: future trouble, future problems) after + afflicted
A more verbose definition of 後患 is ”future problems caused by a failure to take proper precautions at an earlier time.”
The second kanji, 患 (KAN, wazura(u)), breaks down as follows:
串 (KAN: pierce; kushi: skewer)
心 (SHIN, kokoro: heart)The first character strikes me as a clear pictograph of skewered meat. If you eat too many of these, you could develop heart disease, which would indeed be considered “future trouble.”
That’s not the real etymology, unfortunately. According to Kenneth Henshall in A Guide to Remembering Japanese Characters, 串 is likely derived from an older form that showed hands thrusting a stake (not to be confused with “steak,” and is it just me, or are you getting hungry?). The older form meant “to pierce.” Together, the two parts of 患, or “pierced heart,” meant “to grieve” (and 患 still has that meaning in Chinese, says Henshall). The sense then broadened to “afflicted.” And in Japanese, the character acquired the more specific meaning of “being afflicted with a disease.”
Well, then, I should demote the shish kebab and heart disease interpretation of 患 to the status of a mnemonic—one that might come in handy if you encounter 患者 (kanja: patient), which breaks down as afflicted + person.