Dentsu Ventures, the corporate venture capital of Japanese ad agency Dentsu, announced today that it has invested an undisclosed sum in San Diego-based Cue, the startup developing a health tracking device under the same name. Financial details have not been disclosed. For Dentsu Ventures, this is the fifth investment in a startup followed by Jibo (communication robot), Agolo (curated content generation), Nextbit (cloud-based smartphone), Sensai (big data analysis), and others....