(4)

"Yumi"
Sachiko called soon after the car entered the avenue.
"Are you strong at car rides?"
"Strong at taking car rides...? Do you mean whether I easily go carsick?"
Yumi rephrased the question. Based on previous experience, Yumi grew prudent in making sure she didn't misunderstand what she heard.

"What else do you think it can mean?"
"Nothing. I just want to check whether you might be asking if I know a lot about car brands."
"Silly."
Sachiko-sama gave a faint laugh.

"Well, why do you ask so?"
"If you need this, take it."
Sachiko-sama took out a flimsy pack. Opening it, Yumi found pink pills lined up in it.
"This... Is this carsick relief medicine?"
That would be the logical deduction along the conversation flow.
"Yes. I took it at home before I came."
"I see."

The neatly aligned pack of pills had two holes, indicating that two pills had been used. Now that she mentioned it, on Kashiwagi-san's car cruise a few days ago, Sachiko was said to get terribly sick, wasn't she?
Well, her sickness might be accumulation of unfortunate factors, such as riding on an unfamiliar car, bad road conditions, tiredness, and (probably) Kashiwagi-san's terrible driving. However, this time it would be a long trip, so Sachiko-sama might be worried even though they were travelling by the home car.

"I am fine."
Yumi refused Sachiko-sama's offer, and Sachiko-sama muttered "Oh?" with a flash of disappointment on her face. Probably Sachiko-sama would like me to follow her suit? Yumi's idea came too late though, as the pack of pills was already stuffed back to the pouch.

Maybe Onee-sama would feel happy if I say now "On second thought, may I take one?" Yumi reflected, and unconsciously toyed with the zipper of the temperature-preserving case on her knees. Sachiko-sama pointed and asked.
"What is this?"