In this era of fast decline in biodiversity, it is necessary to know what drives the composition and dynamics of hidden soil animal biodiversity to predict ecosystem-level consequences of the environmental change via changing litter decomposition process and invertebrate biodiversity. Soil fauna live in habitats composed of plant litter, the quality of which depends on trait afterlife effects of the plant community. However, we still cannot link plant and the soil fauna community, likely because plant litter traits have only been evaluated in terms of a food source. To plug this vital gap, we proposed a trait-based framework focusing on the concept that soil fauna live in "a house made out of food". To understand habitat quality of litter for soil fauna, we started to assess physical traits related to litter size and shape spectrum (SSS) as well as litter traits related to plant economics spectrum (PES). In this presentation, we introduce a conceptual diagram to explain how PES- and SSS-traits of single litter particle affect litter pack traits directly related to habitat environment for soil fauna.