This Interview is a part of the Special Issue of Communications in Mathematical Analysis dedicated to late Prof. Tosio Kato on his 100th birthday. We extend our deepest thanks to Prof. Hitoshi Kitada for dedicating his paper "Wave Operators and Similarity for Long Range N-body Schrodinger Operators" to Prof. Tosio Kato. Further, we thank him for accepting to answer to our questions.

We consider asymptotic behavior of $e^{-itH}f$ for $N$-body Schrödigner operator $H=H_{0}+\sum_{1 \leq i < j \leq N } V_{ij}(x)$ with long- and short-range pair potentials $V_{ij}(x)=V_{ij}^L(x)+V_{ij}^S(x)$ $(x\in {\mathbb R}^\nu)$ such that $\partial_x^\alpha V_{ij}^L(x)=O(|x|^{-\delta |\alpha|})$ and $V_{ij}^S(x)=O(|x|^{-1-\delta})$ $(|x|\to\infty)$ with $\delta>0$. Introducing the concept of scattering spaces which classify the initial states $f$ according to the asymptotic behavior of the evolution $e^{-itH}f$, we give a generalized decomposition theorem of the continuous spectral subspace ${\mathcal H}_c(H)$ of $H$. The asymptotic completeness of wave operators is proved for some long-range pair potentials with $\delta>1/2$ by using this decomposition theorem under some assumption on subsystem eigenfunctions.