Cashmere sweater
The magic: light, warm and classy. Even suitable for most work situations.
Silk neckscarf
The magic: takes up zero space and gives you extra warmth in all seasons.
ibuprofen
The magic: cures everything - pain, headache, fever, sunstroke, bruises, sprained joints, cold.
white cotton t-shirt
The magic: all-purpose shirt for casual moments. Doubles as undershirt (with V-neck to wear under a shirt). Triples as pajamas after wearing it a couple of days.
shaving oil (in a tiny Muji spray bottle)
The magic: takes up no space, gives the smoothest shave and lets you shave under the shower. It also extends blade life (prevents oxidation) compared to using shaving foam. I use baby oil because it sprays well, but almond oil is also good, and I suspect any oil can do.
Tip: shaving with oil has one drawback: hair mixed with oil tends to clog the razor, so you need running water to keep the blades clean as you go. If they really get clogged, then just use a little soap on the blades.
mini laptop plug
The magic: plug in the laptop charger directly into the power socket, leave the bulky AC cable at home. (Bought on the internet, look for "IEC320 C5 plug" for 3-prong or "CEE7/16 to IEC C7" for 2-prong).
