The last declension that we haven't yet talked about is the 5th declension, the smallest and probably the strangest declension of all five.

The masculine words have these endings:

vanduo (water)
vandens
vandeniui
vandenį
vandeniu
vandenyje
vandenie!

vandenys
vandenų
vandenims
vandenis
vandenimis
vandenyse
vandenys!

Note that the en part is considered a part of the stem. Everything else is the endings.

All the words of this declension are masculine, except for two which are feminine:

sesuo (sister)
duktė (daughter)

What is more, the stem ends in er, not in en:

sesuo
sesers
seseriai
seserį
seserimi, seseria
seseryje
seserie!

seserys
seserų
seserims
seseris
seserimis
seseryse
seserys!

Duktė doesn't have an uo:

duktė
dukters
dukteriai
dukterį
dukterimi, seseria
dukteryje
dukterie!

dukterys
dukterų
dukterims
dukteris
dukterimis
dukteryse
dukterys!