The phrase is the motto of Professor Masao Kawai. He was born and grew up in Tamba-Sasayama, a small city, rich with nature. Later, when he became an honorary citizen, the city asked him to donate the calligraphy of his motto for it to be sculpted into a stone monument. The celebratory monument was set on the bank of Sasayama River, which he loved (Fig. 5). It is a pleasant memory for me to have taken a souvenir photo with him and his wife in front of the monument. “Play in nature” was surely his strong belief throughout his entire life. He played in nature when he was a young boy, and continued to play in nature when he eventually became a scientist and a writer of children’s literature as well.
In 1974, I became a graduate student of the Primate Research Institute (PRI) of Kyoto University. The graduate program in PRI started in 1972, so that I was a third-year student. I belonged to the Department of Sociology and Ecology, which was founded by Professor Kawai. He was my mentor for the 5-year program for my Ph.D. and very kind to me in both official and private aspects of life in PRI, Inuyama. At that time, his junior colleagues and students formed a team to study gelada baboons (Theropithecus gelada) in the highlands of Ethiopia. The team also made efforts to help the country establish a national park in the southern part of Omo Valley.
In the first 2 years of my Ph.D. program, for my master’s degree I was free to choose a research topic. Under Professor Kawai’s supervision, I targeted the Yakushima monkeys (Macaca fuscata yakui). I was very happy to succeed in habituating the wild monkeys without provisioning (Maruhashi 1980, 1981, 1982). In the following 3 years of the doctoral program, Professor Kawai gave me a new mission: pioneering work on hybrids of gelada and anubis baboons (Papio anubis) in Ethiopia. My teammates and I prepared a large amount of equipment for the field research, including two all-wheel-drive jeeps. We successfully shipped them to Djibouti, the port facing onto the Red Sea and the Gulf of Aden. Ethiopia was an empire for several hundred years, before falling into a chaotic period marked by civil wars. Professor Kawai made the decision to stop the fieldwork in Ethiopia, just one week before the scheduled departure. He wrote a book titled The forest provides the origin of primates (Kawai 1979b). The afterword of the book provides some details on those hard times and the difficult decision.
From a wide perspective, Professor Kawai shifted his attention from Ethiopia to Cameroon. He reorganized the research team to focus on mandrills (Mandrillus sphinx) and drills (Mandrillus leucophaeus) living in the tropical rain forests in Cameroon. At that time there were almost no field studies on the two species. They were supposed to have a multilevel society in which the units of one male with multiple females might merge into a larger group. He was very much interested in the evolutionary origins of human-like multilevel society.
For me, the first experience of overseas research was the travel with Professor Kawai. Let me introduce an episode. We were in Paris to change flights for Cameroon. At the time of boarding, I whispered to him, smiling.
Me: “Professor, do you have your passport and boarding pass?”
Professor: “Why not!” Then he paused and said, “Oh, my god, I have no passport!”
Me: “You may have left it at the immigration check.”
Professor looked for it and said: “I found it!” He was relieved, and smiled.
The smile and his shining face reminded me of the face of a boy named Mato. Mato is the main character in his first children’s book Forest school: Animals I have known in Tamba-Sasayama (Kawai 1975). Mato always smiled when he encountered something pleasant. We went to the forests in Cameroon and I was in charge of the study of drills in their natural habitat. However, I am sorry to say that the fieldwork on drills was very difficult due to the high hunting pressure.
Mato Kusayama is the pen name of Professor Kawai. In parallel with his effort as a scientist, he became a well-known writer of children’s literature. He published many books under this pen name. Between 2011 and 2018, when he reached 90 years of age, he published a series of four books on Kenji Miyazawa (1896–1933), a very popular poet and writer of children’s literature in Japan. Kenji passed away at the young age of 37 years, so his reputation was formed only after his death. Professor Kawai kindly gave me the four books on Kenji, titled Understanding the soul of Kenji Miyazawa. Professor Kawai included a private card when he presented me with these books. The message on the card said: “Kenji wrote the books for children. There have been more than 300 books published since he died. However, all of them are for the adults, and no book has targeted children. I dared to write up this series of books on Kenji to talk to the young readers. During the challenge, I battled against the constraints of vocabulary and expression.”
When I met Professor Kawai in 2016, he said: “My heart continues to beat. My brain continues to express various ideas.” His wife, Ryoko-san, was sitting next to him and said: “My mission is to serve for his long life.” She also mentioned: “I don’t know what he writes, but he used to get up at 6 o’clock in the morning and always wrote something, till noon.” His last book is titled DOEKURU expedition party (Kusayama 2018; Fig. 6). It is a fantasy about children and animals led by a man nicknamed “Wind” on a mission to find the Doedicurus in South America. Doedicurus is a huge, 4-m-long, armadillo-like mammal during the Pleistocene, and it went extinct about 11,000 years ago. The children’s book is 732 pages. It was published in 2018, when he was 94 years old.
The last book contains the following message by the main character: “Books were the teacher of mine. I have another teacher: that is nature. Nature brings us a lot of wonder.” I imagine, in his next life, Professor Kawai may continue to play in nature, talking and interacting with his beloved animals.