Pointing at people or things is considered rude in Japan. Instead of using a finger to point at something, the Japanese use a hand to gently wave at what they would like to indicate. When referring to themselves, people will use their forefinger to touch their nose instead of pointing at themselves.
Prolonged eye contact (staring) is considered rude. Don't show affection, such as hugging or shoulder slapping, in public. Never beckon with your forefinger. The Japanese extend their right arm out in front, bending the wrist down, waving fingers.
In Japan, crossing one's legs is seen as disrespectful. It is because when you do this you show the bottom of your feet to guests, and since they have picked up dirt, you are showing that dirt to your guests.
Blowing your nose at the table, burping and audible munching are considered bad manners in Japan. On the other hand, it is considered good style to empty your dishes to the last grain of rice.
In fact, in Japanese culture, people are taught not to maintain eye contact with others because too much eye contact is often considered disrespectful. For example, Japanese children are taught to look at others' necks because this way, the others' eyes still fall into their peripheral vision [28].
Avoid things like tank tops, shorts, and mini-skirts. Opting for more conservative clothing is always a safe bet even if you don't plan to visit temples or shrines. It's also generally frowned upon for women to show cleavage. Clothing with offensive messages or designs.
If you are not wearing socks, it is polite to bring a fresh pair of socks to wear after removing your outdoor shoes because entering someone's house barefoot is not considered well mannered, although acceptable in informal situations. Slippers can generally be worn anywhere except when entering rooms with tatami floor.
Do not address other people using their first names. In Japan, you do not address other people by using their first names like how things usually are in the Western world. That is not considered polite, especially if you are talking to a superior, someone older than you, or someone you meet for the first time.
Gifts that come in sets of either 4 or 9 are considered to be very unlucky in Japan. This is because “shi” (the Japanese word for “four”) also means “death”, while “ku” (the Japanese word for “nine”) also means “suffering”. Conversely, gift items offered in pairs are considered to be very lucky.
Pointing the finger is considered rude in Japanese culture because the person pointing is associated with explicitly calling out the other individual for their wrong behavior or actions. Repeatedly pointing while speaking to another person is considered a sign of extreme frustration or an expression of dissatisfaction.
Loud chatter or behavior is usually frowned upon because it invades others' space. Avoid talking on the phone (put it on silent) and send messages instead. Eating and drinking should only be done on long-distance trains.
Wear slip-on shoes
While flip flops are a big no-no for most occasions (save for a trip to the beach or a midnight run to the conbini), comfy ballet flats, loafers, boat shoes, or even a nice pair of slip-on sneakers are practical options. You might also notice that open-toed shoes and sandals are uncommon.
White should be avoided, although at a more casual wedding you may be able to wear black. On the other hand, it's not all rules and customs. Bright colors and patterns are welcome at a wedding, as it is a celebration after all — although anything too flamboyant may be seen as inappropriate.
The Japanese people didn't wear bras or underwear in the past. They wore Hadajyuban (肌襦袢) and Susoyoke (裾よけ) just to hide their skin and body shape. Nowadays, many people hesitate to obey the so-called "No Bra, No Underwear" rule, they normally wear ordinary bras and underwear.
Actually, tattoos are fine in Japan. They're not illegal in any way. You may even see some people walking around with fashion tattoos, especially in Tokyo. Although some people in Japan have tattoos, they are usually hidden underneath clothing.
Never hugging or kissing
In Japan, touching another person's body is considered rude, even with friends or family. Hugging and kissing are mostly for couples.
Avoid physical contact. Nose blowing in public is considered very rude, as are yawning, coughing and using toothpicks without covering the mouth.
PDA or public displays of affection might be common in your country but in Japan most couples will avoid kissing or hugging in public. Holding hands is popular, though.
Always finish your meal!
The Japanese consider it rude to leave food on your plate, and even more so to order more food when you haven't finished everything you've already got. This is related to one of the fundamental concepts in Japanese culture, mottainai, which is a feeling of regret at having wasted something.
Japanese tend not to eat while walking along or standing around on the street. However, it is acceptable to drink while standing aside a vending machine. Eating and drinking on local trains, but not long distance express trains, is also frowned upon.
Unlike Europe and the U.S., there is no culture in Japan in which sunglasses are worn on a daily basis, and Japanese people are not familiar with wearing sunglasses.