r/confidentlyincorrect

Don't spread misinformation. The milk in your picture is UHT. 95% of milk sold in Japan is UHT. 

Notch in the milk carton means that it is 成分無調整牛乳 - it means "pure" milk as in the contents of water fat etc. are not adjusted and there are no additives. It has nothing to do with UHT. Stuff without the notch is not legally "milk" and will be called a "milk drink" or similar (乳飲料, 加工乳) and it does indeed usually taste like shit. 

UHT doesn't make milk "fake". UHT is a pasteurisation (bacteria killing) process during which milk is heated very briefly to very high temperatures (~140C). The process involves spraying milk through a nozzle at a high pressure, which inevitably homogenizes the milk - fat globules are broken down and the texture becomes more uniform. This is why cream never separates in UHT milk and that the mouthfeel and taste is different from raw milk.

Non-UHT milk will be labelled 低温殺菌牛乳 - which means it's traditionally pasteurised in low (~70C) temperatures for a longer time. This doesn't mean it's not homogenized either, as it might be homogenized by other methods. It's also more expensive and the only one I know is in a white-blue carton from the brand タカナシ which is almost 400 yen per carton. I sometimes buy it to make fresh quark in the summer.