The country is in the midst of a heat wave, and with a lower than average rainfall there's a serious water shortage. As such, Chinami Kawamura and the rest of her school's swim club are relegated to running laps instead of swimming them, and in the heat of the mid-day sun, the young girl collapses. While unconscious, Chinami finds herself beside a clear, sparkling river in a deserted rural village where she meets a young boy named Sumio and his elderly father. But even after she awakens and returns to reality, Chinami continues to pass out and visits the same refreshing place - much to her mother's concern...
Kanae's husband disappeared without a trace while on a union trip. Though usually headstrong and independent, the woman becomes plagued with worry over what happened to him, and is unable to move on with her life. Thus, Kanae decides to hire a private investigator, and keeps running the public bathhouse to the best of her abilities, but the detective who shows up is disheveled and eccentric. As he tries to figure out the truth about her husband, Kanae must deal with the stress from a work-intensive job, meddlesome neighbors, and recurring nightmares in which she is drowning.
Undercurrent and Suiiki are about people who, after a great personal tragedy, are unable to let go and move on in their lives. Both are light mystery stories set in small towns, with an unhurried pace, a somber tone, and watery settings.
Suiiki and the ninth chapter of White Clouds have a lot of similarities, which I will refrain from mentioning due to spoilers. However, both manga (including the entirety of White Clouds, not just this one chapter) have a similar somber, introspective tone, and will likely appeal to the same audience.