In this paper, we consider the tokoro-da sentences that appear in Japanese textbooks from the viewpoint of the relationship between the speaker and the nominative case and clarify (1) and (2). (1) In the same section, first-person nominative tokoro-da sentences and non-first-person nominative tokoro-da sentences are mixed and treated at the same level. (2) Japanese textbooks do not clearly indicate the conditions for use of the non-first-person nominative tokoro-da sentence and the relationship between the nominative case and the speaker. Based on the above, we propose (3) and (4). (3) The first-person nominative tokoro-da sentence is introduced first, and treated separately from the non-first-person nominative tokoro-da sentence. (4) For non-first-person nominative tokoro-da sentences, it is necessary to clearly indicate the conditions of use and the relationship between the speaker and the nominative case.