import pandas as pd

df1 = pd.DataFrame(
    {
        "writer": ["kadowaki", "terada", "takanory", "ryu22e"],
        "value": [1, 2, 3, 4],
    }
)
df2 = pd.DataFrame(
    {
        "writer": ["ryu22e", "fukuda", "kadowaki"],
        "value": [5, 6, 7],
    }
)
print(df1.merge(df2, how="inner", on="writer"))