Meihou saw Gojyo fighting in a street brawl that caused quite some commotion. Gojyo won of course, no question there. The little girl became interested in him and pursued him relentlessly for the rest of the day. Gojyo tried to ditch her.
"How am I supposed to pick up chick with this buggered eater following me."
---Sha Gojyo; Episode 14
Eventually he gave up, but not without serious effort into losing her. After Gojyo finally caved, Meihou asked our young (who's 22 at the time) Gojyo on a "date".
During the date, Meihou finally gets to tell Gojyo her reasoning. Why she was following him all day. Turns out she wants to hire his services for the night. Don't be scared if you get the wrong idea, Gojyo did too at first. The reason she wants him is because she needs his help. She doesn't have any money, but offers him a green pendant that obviously has sentimental value to the young girl. She tells Gojyo about how her caravan was raided by a demon. Her mother [ who is wearing the pendant in the flashback ] hides her during the attack and when Meihou climbs out of her hiding place the next morning, the camp is in ruins and there is no sign of her parents or the other people they were traveling with. All that's left it her mother's pendant at her feet.
When we return to the present, Meihou has broken down into tears and Gojyo understand why she was so persistent. He agrees, saying that she's hired herself one "Demon Ass-kicker".
The two of them go into the forest near the village where the youkai that attacked them supposedly lives. They come across an old shed like house that seems abandoned. Gojyo approaches with caution, having had enough experience with demons before hand to suspect what's coming. Inside the house they find Meihou's parents and the rest of the caravan. But at this point the house starts to change. Gojyo rushes the girl out of the house, but gets stuck as the thing turns into a massive collection of vines. Hearing Meihou's scream, Goku, Sanzo and Hakkai, suspicious of youkai activity, show up and, uh, sort of rescue Gojyo. They kill the youkai who's behind all this save the people trapped inside, reuniting Meihou with her family.
Gojyo gave back Meihou's necklace telling her it would look better on her. He tells her to look him up again in 10 years or so when she's older, telling her she'll grow up into a fine woman.