Japan today is increasingly described as a ‘society without ties’ (muen shakai), riddled with anomie and a sense of isolation. Particularly poignant, for many, are the cases of elderly dying at home alone; of hikikomori, or people who choose to withdraw from social life altogether, refusing to leave their bedroom for months or even years; and of homeless and precariously employed men in day-labourer quarters. In this chapter, I argue that loneliness is a moral sentiment, which traces forms of sociality that have become dysfunctional. Loneliness can thus be understood as a form of social critique, pointing to problems in expected forms of social connection while also opening up a space for alternatives.