Note that [S] is a voiceless alveopalatal fricative as in English sheep/.
[ts] is an alveolar affricative, sort of like the middle consonant in 'pizza'.
[tS] is an alveopalatal affricate as in English 'cheap'.
1. [Sitsure] rudeness
2. [te] hand
3. [kata] person
4. [itSi] one
5. [Simasu] doing
6. [san] three
7. [suru] to do
8. [tako] octapus
9. [tSitSi] my father
10. [aSi] leg/foot
11. [natsu] summer
12. [tsu] steal
13. [saru] monkey
14. [isu] chair
15. [ite] be
16. [wataSi] I
17. [kasa] umbrella
18. [tsuru] crane
19. [tomodatSi] friend
20. [hatSi] eight
[s] and [S] are in complementary distribution. [S] occurs before [i]; [s] occurs elsewhere. They are allophones of the same phoneme.