Those famous authors who susan taught can read at "Aozora Bunko". (free/no regist)
http://www.aozora.gr.jp/"Soseki" full name is "Natsume Soseki"(=Soseki Natsume/first name, last name) like this,
http://www.aozora.gr.jp/index_pages/person148.html#sakuhin_list_1(Select the title and open the link for "XHTML" on the next page, also you can download as "zip" file.)
https://en.wikipedia.org/wiki/Natsume_S%C5%8DsekiThis is one of big famous title "Kokoro".
http://www.aozora.gr.jp/cards/000148/files/773_14560.html@ susan
It may be hard to search without full names.
The first three authors are called as their nick is right,
but we(Japanese) do not abbreviate the fourth one "Murasaki Shikibu".
https://ja.wikipedia.org/wiki/%E7%B4%AB%E3%81%AE%E4%B8%8AAlthough she is called "Murasaki no -kimi/-ue" in her title.
@ TrinityE
I do not know where to go in Japan, but there are many big bookstores in big cities,
https://goo.gl/Upe6dNalso many secondhand shops, "BOOKOFF(book off)" is the largest.
https://www.bookoff.co.jp/shop/Non-famous titles are very cheap, you can purchase it from 108Y.
(about 1 USD, including sales tax 8%).
https://www.hardoff.co.jp/wp/wp-content/uploads/2014/10/12021_2.jpgThis is their online shopping web bargain price of modern Junbungaku(pure literature/belles-lettres ),
some titles are original of famous movies and TV-dramas.
http://www.bookoffonline.co.jp/display/L001,pr=u-110,bg=122104,st=u,
(You can not order from overseas.)
And, public libraries are also good, just you can not rent.
https://goo.gl/pNrNGsIf not a school closing day, you can also enter the university libraries,
their restaurants are also cheap and tasty, if possible add it in rainy day plan.
Also if you like manga and want to read a lot,
there are also "manga kissa(cafe)" that you can stay a lot.
https://goo.gl/9MazpbBut you may forgot enough sleep until next morning.
Japan summer is temp and humidity are high a lot,
so people are easy to gather at book stores and libraries where air conditioning worked.
(e-books users also increased very much already, but.)
https://goo.gl/ZRMHbU