## 1 Introduction  
In recent years, interactive systems that humans can operate in natural language are in demand and have been put into practical use. Dialogue systems, such as customer support chatbots on corporate websites, virtual assistants and so on, are becoming part of daily life. Along with the development of relevant technologies, dialogue systems are predicted to build longer-term and closer personal relationships with users [1]. Dialogue systems are expected to build relationships with humans as partners. It has been shown that systems can demonstrate human-like value as communication partners. The media equation, which suggests that interactive systems can be perceived as equally human [2], is widely recognized. Conversations with chatbots have positive psychological effects similar to conversations with humans [3], and apologies from robots have value for people [4]. As a relevant technology, generative AI using large language models is making dialogues with systems more human-like. Systems can generate new sentencesas if they had their own mind. For example, ChatGPT-4 (OpenAI, San Francisco, CA, USA) demonstrated advanced linguistic abilities, answering a theory-of-mind test including a false belief scenario correctly, which matches the performance of six-year-old children [5], and it was recognized as a human in a Turing test [6]. Although advanced linguistic abilities do not show that dialogue systems have their own mind, it has been shown that systems can behave as if they understand people's views and minds like humans. More human-like conversations have been thought to improve relationships between users and systems. Some conversational software applications have been developed to make interactions more human-like, introducing emotions, personas, or personal stories [7; 8; 9]. However, it also has been shown that human-like performance is sometimes perceived as unpleasant [10]. Previous research on chatbots' responses shows some necessary characteristics for positive user experiences, while the answers to each question, choosing the preferred chatbot's response, in the survey were mixed [11]. There is a range of expectations regarding the behavior of human-like systems. In personal relationships, it is natural that people have various ways of interacting with others and perceive them differently, person to person. Systems have become sufficiently human-like to build personal relationships with users, and they are required to adapt to the range. In our other research, individual preferences in system behavior were investigated in terms of relationship compatibility between users and systems to build favorable relationships [12] since personality adaptiveness can become a valuable feature for systems [13]. This paper focuses on social behavior in interactions to build trustworthy relationships. Language is a way to influence human behavior in social interaction. Dialogue systems using text-generating AI would act as the actuators to influence and assist users' behavior, which will help to develop the next AI agents [14], including everyday issues such as healthcare, education, or whole lifestyles [15; 16; 17]. In order to assist and sometimes instruct human behavior via language, it is essential to build trustworthy relationships because humans are unlikely to accept words without trust. By interacting with each other, especially through conversation, people adjust rules and common sense, building relationships of trust and cooperation. The more personal the relationship, the more important the interaction. Dialogue systems, which talk sufficiently human-like and work personally in daily life, would need to build trustworthy relationships through interactions similarly. The importance of interactions with one another is shown in other perspectives. Regarding cognition of non-living things as living, when the objects indicate relationships interacting with each other, even if the objects are geometric figures, it is known that a sense of animacy and empathy for the objects can occur [18; 19].