Se is the next sound in the chart, it sounds pretty close to the English word ‘say’, and is represented by せ in hiragana and セ in katakana.
Seijitsu (せいじつ) is a -na adjective which a dear friend has used to describe me recently. It means honest, sincere, or genuine. I have been trying to build a relationship where we discuss things frankly but from the heart – straightforward but kindly. I was happy when she labeled me thus. We can write this in kanji as 誠実.
She also labeled me with another adjective that fits today, so I’ll throw that in as well: sensai (せんさい), which is fine or delicate. I let her know that guys normally don’t want to be called delicate; however, I was happy to receive her praise. This one can be written in kanji as 繊細.
Nothing was really jumping out at me for katakana that meets the two rules of: not usually found in language books; and useful in common conversation. I’ll go with serohan or serohanteepu (セロハン・セロハンテープ). These are just “cellophane” and “cellophane tape” dramatically changed. This is one of the cases where the katakana sound chosen is not the best fit for sound, but seems to have been chosen merely based on what English letter was in the word. (I guess if we made our spelling more phonetic, it would be easier on people who are adopting our words.) I find this word useful because merely asking for teepu often yields other kinds of tape and asking for cellophane tape (in English) gets me blank stares because the sound is so different. If you don’t tape a lot of stuff, this might not be as useful.
Sorry this is getting posted so late. I fell asleep on the computer Sunday night.