IP-based Wireless Sensor Network (IP-WSN) is one of the essential elements enabling Internet of Things (IoT). However, IP-WSN imposes great challenges due to low processing resources and strict energy constraints of sensors. Various routing protocols for IP-WSN have been proposed considering low-cost communication with resource-constraint and typical traffic patterns like multipoint-to-point, but most of routing protocols causes problems incurring inefficient route or/and consuming many processing resources. Especially, as far as point-to-point (P2P) traffic is concerned, those routing protocols incur triangular detour routes and require many processing resources at intermediate nodes where P2P traffic is an important traffic pattern. To address these challenges, we propose the Stateless P2P Routing protocol (SPR) based on shortcut tree routing algorithm which is our previous study. SPR can deliver a packet to the node having the smallest remaining hop count among neighbors without additional control overhead, instead of always delivering a packet to a parent or children along tree routes. SPR also provides a nearly stateless routing in that SPR determines a route through hierarchical address structure and one hop neighbor information without having to store global routing state. We implement SPR in our IP-WSN platform named SNAIL and conduct a simulation and a measurement to verify the performance of SPR. The simulation results show SPR provides improved hop count compared to HiLow and RPL. It also provides reduced memory usage and the number of control packets compared to RPL. Additionally, the measurement results show SPR provides decreased round trip time and increased packet delivery ratio compared to HiLow and RPL.