How do Japanese individuals respond to pain, For example do they
respond the same way as Caucasian individuals- are they stoic or not,
are they tolerant or intolerant?

Dear atwitsend, 

Response to pain varies in many cases among different individuals, not
only because of their ethnicity, but also according to their gender
(women are usually under-medicated than men), age (the elderly have
less pain tolerance), their physician's attitude (some doctors
underestimate the patient's pain level) and other factors.

However, there could be factors that are ethnically related. For
example, it has been revealed, that doctors under-medicate African
American and Hispanic patients. This could be allocated to many
factors - "including providers' perceptions of race and ethnicity,
racism and bias on the part of health care providers, language
barriers, patients' socioeconomic status, and effects of race and
ethnicity on patient-physician communication and on clinical
assessment of pain" (source: Bonham VL. "Race, ethnicity, and pain
treatment: Striving to understand the causes of and solutions to the
disparities in pain treatment" J Law Med Ethics. 2001; 29: 52-68, as
abstracted in <http://www.partnersagainstpain.com/html/profed/profed.htm?pg=6323&section=profed>).

In other words, even when there are differences between different
patients from different ethnic groups, they might not always be
correlated with their ethnicity as such (or, if to quote your own
question "do they
respond the same way"), but with the doctors' attitudes towards them.

A clinical research conducted in Japan in 1998 revealed that the
Japanese respond to pain similarly to patients of other groups in
other countries. Previous concepts on Japanese pain tolerance or pain
management may have been partially based on the fact that the Brief
Pain Inventory was not translated to Japanese until that study
(source: Uki J, Mendoza T, Cleeland CS, Nakamura Y, Takeda F., "A
brief cancer pain assessment tool in Japanese: the utility of the
Japanese Brief Pain Inventory--BPI-J." _J Pain Symptom Manage_ 1998
Dec;16(6):364-73 as abstracted in
<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9879161&dopt=Abstract>).


Further Reading 
=============== 
Harada N, Chiu V, Tsuneishi C, et al. Cross-cultural adaptation of the
SF-36 health survey for Japanese American elderly. Journal of Aging
and Ethnicity 1998;1(2):59-80.

Mercedes Tira Andreim, "Asian Americans Get Inferior Health Care, Says
US Congress Report" Asian Fortune
<http://www.asianfortune.com/july02/APA%20Get%20Inferior%20Health%20Care.htm>

Sharts-Hopko, N. C. (1996). Health and illness concepts for cultural
competence with Japanese clients. Journal of Cultural Diversity, 3(3),
74-79.

Walker, A. C., Tan, L., & George, S. (1995). Impact of culture on pain
management: An Australian nursing perspective. Holistic Nursing
Practice, 9(2), 48-57.

You might also want to check www.culturaldiversity.org, a site that
deals with cultural differences.

My search strategy included "tolerance to pain" and the word
"Japanese" or terms such as "pain management", sometimes added by
"ethnicity". Except for Google, I searched in medical databases.

I think that answered your question. However, if you need any
clarifications, please let me know.