Tsundoku·The act of leaving a book unread after buying it, typically piled up together with other such unread books. Source
Hikikomori·The phenomenon of reclusive adolescents or adults who withdraw from social life, often seeking extreme degrees of isolation and confinement. Source
別腹(Betsubara)·Literally extra stomach, usually used by children to explain why they have room for dessert even when they are already full from dinner. Source
Aizuchi·To interject into a monologue with a short phrase to indicate understanding and active listening. Source
Thomasson·A useless relic or structure that has been preserved as part of a building or the built environment. Source
Mikkabouzu 三日坊主·Literally A three-day monk, meaning someone who gives up too easily or can't stick to something. Source
Kenjataimu·The period after orgasm when a man is free from sexual desire and can think clearly. Source
痛車 (itasha)·A car painted with anime characters (lit: painful car, because it's painful to look at). Source
干物女 (Himono-onna)·(noun) A woman with little to no interest in relationships, and that prefers to stay at home lazying around; especially when showing a social face while outside. Source
Honne (本音)·The contrast between what one truly believes honne and what beliefs one displays in public tatemae. Source
Hibakusha·A term used to refer to those who survived the atomic bombings of Hiroshima and Nagasaki; literally translates as explosion-affected people. Source
立ち読み·Tachiyomi (lit. standing reading) standing and reading (sometimes for lengthy periods) through magazines or books before/without purchasing them. Usually seen at corner shops and bookstores. Source