Consists of house/roof 宀 and the element 夗. The latter probably lent its sound, and had perhaps the connotation of to bend (one’s body). 夗 can be analysed as night/moon 夕 and bent body 卩/㔾 but the element on the left side may have been different at an earlier stage. Scholars disagree about the original meaning of 宛 (hemispherical roof and turn in one’s sleep are two suggestions).¹ In classical Chinese 宛 was loaned to write a word with meanings pliant, supple; yielding. In Japanese it also came to be used for ate, specifically in the meaning addressed to, which according to one scholar may have been derived from the older meaning yielding.² Suggest to take 宀 simply as house, 夕 as night and 㔾 as curved up body.
Mnemonic: Your address is the home where you curve up in bed at night
The original function of 宛 (or its likely phonetic 夗 for that matter) is unknown. However, it is interesting to note that a lot of words that are written with graphs that have 宛 or 夗 as an element have connotations of round, bend, yielding, etc.
Most scholars think that 㔾 in 宛 depicts a bending person. Ochiai insists that the oracle bone shape depicts a person with its head hanging down and only later the exaggerated head was separated and redrawn as night/moon 夕, and the person as bending person. As often a lot of confusing variants have been found, among them bronze graphs that show meat 月/肉 instead of night/moon 夕.
Scholars trying to get at the original meaning of 夗 have suggested bend the body, fall down, turn in one’s sleep. For 宛 they have suggested hemispherical roof, again bend the body and again turn in one’s sleep (the latter takes 宛 as “an embellished variant of 夗”).
宛 was loaned to write other words later on. In classical Chinese it pointed to a word “pliant, supple; yielding.” In Japanese there still exists enten 宛転/宛轉 (a compound borrowed from classical Chinese) with meanings like “eloquent; fluent; smooth-spoken” and “nicely shaped eyebrows.” The word enzen 宛然 (“as if; the very thing itself”) comes from an another expression in Chinese that 宛 was used to write for.
In Japanese one is most likely to see 宛 being used to write ate, in its meaning “address; addressed to.” Ironically 宛 is also used to write the expression ateji 宛て字 (also 当て字), which indicates either a character that is used only for its sound to use a different word (a loan graph, like 宛 itself in Chinese) or used more or less arbitrarily to write a different word (its use in Japanese to write 宛 for ate feels arbitrary, as it does not seem to derive from usage in Chinese; however Henshall suggests it could be a derivation from the meaning “yielding”).
For its modern Japanese meaning of “address” 宛 can be reinterpreted to make more sense. The element house/roof 宀 has obvious relevance for “address”. Further, there is someone at home (curved up 卩/㔾 in bed at night 夕 ?). Subsequently a mnemonic could be: your address is the home 宀 where you curve up 㔾 in bed at night 夕.