From the standpoint of Applied Ontology, we have challenged the problem of causality on the premise that it is real. As a result, it was shown in the former paper the following three items: (1) causation can be mapped to function, and hence it is possible to talk about causation in terms of function, (2) Cause can be divided into four subfunctions such as Achieve, Prevent, Allow and Disallow by introducing two dimensions of direct/indirect and positive/negative, and (3) using Achieve the other three subfunctions are defined and the essence of causality lies in Achieve. However, elucidation of Achieve itself was left incomplete. In this paper, we first restructure the results obtained in the former paper and summarize it so that the results will become clearer than the original paper. Then, the nature of Achieve is revealed to give a world first solution to the problem of what causation is.