No.
overt method
The theme of the story "at last this fragrance", is about the concept of "attachment".
concept mall is a "theme" mall, eg. Disney land theme with 7 dwarfes and snow white. You could use a Jurassic park theme with dinosaurs and tropical forest. Concept only means certain theme or main idea of marketing. This could be popular but doesn't necessarily go over well.
the THEME
A theme park is an amusement park built around a central idea or concept.
covert = hidden overt = out in the open/clear
Overt (opposite meaning)
the man's overt mistreatment of his dog shocked the neighbors.
motif, central idea, concept
That is the correct spelling of "thematic" (related to a theme or concept).
An overt manifestation of learning would be a clear demonstration of new knowledge or skills that were not present before. This could be seen through improved performance in a task, the ability to explain a concept in one's own words, or successfully applying new information in a real-world context.
Overt means open, so an overt gay person is someone who is prepared to show that he or she is gay, usually by their actions, their dress, or their conversation.