Question:
Which team did Mathias Kouo-Doumbé play for in May, 2006?

Context:
 Mathias Kouo-Doumbé plays for Plymouth Argyle F.C. from Jan, 2004 to Jan, 2009. 
 Mathias Kouo-Doumbé plays for Milton Keynes Dons F.C. from Jan, 2009 to Jan, 2013. 
 Mathias Kouo-Doumbé plays for Hibernian F.C. from Jan, 2001 to Jan, 2004. 
 Mathias Kouo-Doumbé plays for Northampton Town F.C. from Jan, 2013 to Jan, 2014.

Answer:
Plymouth Argyle F.C.