LNCS 13856 is now available online. You can find information about it at

https://www.springer.com/978-3-031-36190-6

or access the online version at

http://link.springer.com/openurl.asp?genre=issue&issn=0302-9743&volume=13856

Authors and conference participants have free access from the protected page (password required)
https://www.ai-gakkai.or.jp/isai/proceedings-of-jsai-isai-2021-workshops

You can access the Forthcoming Proceedings list, the Conference Acronym Index, the Instructions for Authors, and various other useful pieces of information from here
[LNCS homepage]